diff --git a/checkin_notes b/checkin_notes
index 49c2e06629..f2b9d47c94 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -12077,3 +12077,12 @@ Rom    3 Dec 2007
         
     client/
         http_curl.C, .h
+
+Charlie 4 Dec 2007
+    Mac: Update build scripts and documentation for x86_64 support.
+
+    mac_build/
+        buildcurl.sh
+        buildjpeg.sh
+        BuildMacBOINC.sh
+        HowToBuildBOINC_XCode copy.rtf
diff --git a/mac_build/BuildMacBOINC.sh b/mac_build/BuildMacBOINC.sh
index d5f3ab386a..5471852d1e 100644
--- a/mac_build/BuildMacBOINC.sh
+++ b/mac_build/BuildMacBOINC.sh
@@ -22,7 +22,7 @@
 #
 ##
 # Script for building Macintosh BOINC Manager, Core Client and libraries
-# by Charlie Fenton 2/17/06
+# by Charlie Fenton 12/4/07
 # with thanks to Reinhard Prix for his assistance
 ##
 
@@ -31,10 +31,10 @@
 ##     cd [path]/boinc/mac_build
 ##
 ## then invoke this script as follows:
-##      source BuildMacBOINC.sh [-dev] [-noclean] [-all] [-lib] [-client] [-help]
+##      source BuildMacBOINC.sh [-dev] [-noclean] [-no64bit] [-all] [-lib] [-client] [-help]
 ## or
 ##      chmod +x BuildMacBOINC.sh
-##      ./BuildMacBOINC.sh [-dev] [-noclean] [-all] [-lib] [-client]
+##      ./BuildMacBOINC.sh [-dev] [-noclean] [-no64bit] [-all] [-lib] [-client] [-help]
 ##
 ## optional arguments
 ## -dev         build the development (debug) version (native architecture only). 
@@ -43,6 +43,8 @@
 ## -noclean     don't do a "clean" of each target before building.
 ##              default is to clean all first.
 ##
+## -no64bit     build 32-bit binaries only, no x86_64 architecture
+##
 ##  The following arguments determine which targets to build
 ##
 ## -all         build all targets (i.e. target "Build_All" -- this is the default)
@@ -60,26 +62,8 @@ doclean="clean"
 buildall=0
 buildlibs=0
 buildclient=0
-
-DarwinVersion=`uname -r`;
-DarwinMajorVersion=`echo $DarwinVersion | sed 's/\([0-9]*\)[.].*/\1/' `;
-# DarwinMinorVersion=`echo $version | sed 's/[0-9]*[.]\([0-9]*\).*/\1/' `;
-#
-# echo "major = $DarwinMajorVersion"
-# echo "minor = $DarwinMinorVersion"
-#
-# Darwin version 9.x.y corresponds to OS 10.5.x
-# Darwin version 8.x.y corresponds to OS 10.4.x
-# Darwin version 7.x.y corresponds to OS 10.3.x
-# Darwin version 6.x corresponds to OS 10.2.x
-
-if [ "$DarwinMajorVersion" = "9" ]; then
-    # OS 10.5
-    style="Deployment"
-else
-    style="Deployment-no64"
-    fi
-fi
+no64bit=0
+style="Deployment"
 
 while [ $# -gt 0 ]; do
   case "$1" in 
@@ -88,16 +72,11 @@ while [ $# -gt 0 ]; do
     -all ) buildall=1 ; shift 1 ;;
     -lib ) buildlibs=1 ; shift 1 ;;
     -client ) buildclient=1 ; shift 1 ;;
-    * ) echo "usage:" ; echo "cd {path}/mac_build/" ; echo "source BuildMacBOINC.sh [-dev] [-noclean] [-all] [-lib] [-client] [-help]" ; return 1 ;;
+    -no64bit ) no64bit=1 ; shift 1 ;;
+    * ) echo "usage:" ; echo "cd {path}/mac_build/" ; echo "source BuildMacBOINC.sh [-dev] [-noclean] [-no64bit] [-all] [-lib] [-client] [-help]" ; return 1 ;;
   esac
 done
 
-if [ "${style}" = "Development" ]; then
-    echo "Development (debug) build"
-else
-    echo "Deployment (release) build"
-fi
-
 if [ "${doclean}" = "clean" ]; then
     echo "Clean each target before building"
 fi
@@ -118,28 +97,54 @@ fi
 version=`uname -r`;
 
 major=`echo $version | sed 's/\([0-9]*\)[.].*/\1/' `;
-minor=`echo $version | sed 's/[0-9]*[.]\([0-9]*\).*/\1/' `;
+# minor=`echo $version | sed 's/[0-9]*[.]\([0-9]*\).*/\1/' `;
 
 # echo "major = $major"
 # echo "minor = $minor"
 #
+# Darwin version 9.x.y corresponds to OS 10.5.x
 # Darwin version 8.x.y corresponds to OS 10.4.x
 # Darwin version 7.x.y corresponds to OS 10.3.x
 # Darwin version 6.x corresponds to OS 10.2.x
 
-if [ "$major" = "8" ]; then
-echo "Building BOINC under System 10.4"
+if [ "$major" -lt "8" ]; then
+    echo "ERROR: Building BOINC requires System 10.4 or later.  For details, see build instructions at "
+    echo "boinc/mac_build/HowToBuildBOINC_XCode.rtf or http://boinc.berkeley.edu/mac_build.html"
+    return 1
+fi
+    
+if [ "$major" -gt "8" ]; then
+    echo "Building BOINC under System 10.5"
+else
+    echo "Building BOINC under System 10.4"
+fi
+
 if [ ! -d /Developer/SDKs/MacOSX10.3.9.sdk/ ]; then
     echo "ERROR: System 10.3.9 SDK is missing.  For details, see build instructions at "
     echo "boinc/mac_build/HowToBuildBOINC_XCode.rtf or http://boinc.berkeley.edu/mac_build.html"
     return 1
 fi
+
+if [ "${style}" = "Development" ]; then
+    echo "Development (debug) build"
+elif [ "${no64bit}" = "1" ]; then
+    style="Deployment-no64"
+    echo "Deployment (release) build for architectures ppc, i386"
+elif [ ! -d /Developer/SDKs/MacOSX10.5.sdk/ ]; then
+    echo "************************************************************************"
+    echo "**                                                                    **"
+    echo "** WARNING: System 10.5 SDK not found.  Building 32-bit binaries only **"
+    echo "**                                                                    **"
+    echo "************************************************************************"
+    style="Deployment-no64"
+    echo "Deployment (release) build for architectures: i386, ppc"
 else
-    echo "ERROR: Building BOINC requires System 10.4 or later.  For details, see build instructions at "
-    echo "boinc/mac_build/HowToBuildBOINC_XCode.rtf or http://boinc.berkeley.edu/mac_build.html"
-    return 1
+    style="Deployment"
+    echo "Deployment (release) build for architectures: i386, ppc, x86_64"
 fi
 
+echo ""
+
 xcodebuild -project boinc.xcodeproj ${targets} -configuration ${style} ${doclean} build
 
 return $?
diff --git a/mac_build/buildcurl.sh b/mac_build/buildcurl.sh
index cebb546dfe..f574b57ce5 100644
--- a/mac_build/buildcurl.sh
+++ b/mac_build/buildcurl.sh
@@ -24,7 +24,7 @@
 # use in building BOINC.
 #
 # by Charlie Fenton 7/21/06
-# Updated for curl-7.17.1 11/15/07
+# Updated 12/4/07
 #
 ## In Terminal, CD to the curl-7.17.1 directory.
 ##     cd [path]/curl-7.17.1/
@@ -42,18 +42,6 @@
 ## Build with gcc-4.0 to link with the BOINC client 
 #
 
-DarwinVersion=`uname -r`;
-DarwinMajorVersion=`echo $DarwinVersion | sed 's/\([0-9]*\)[.].*/\1/' `;
-# DarwinMinorVersion=`echo $version | sed 's/[0-9]*[.]\([0-9]*\).*/\1/' `;
-#
-# echo "major = $DarwinMajorVersion"
-# echo "minor = $DarwinMinorVersion"
-#
-# Darwin version 9.x.y corresponds to OS 10.5.x
-# Darwin version 8.x.y corresponds to OS 10.4.x
-# Darwin version 7.x.y corresponds to OS 10.3.x
-# Darwin version 6.x corresponds to OS 10.2.x
-
 AlreadyBuilt=0
 
 if [ "$1" != "-clean" ]; then
@@ -62,14 +50,13 @@ if [ "$1" != "-clean" ]; then
     fi
 fi
     
- if [ "$DarwinMajorVersion" = "9" ]; then
-    # OS 10.5
+ if [ -d /Developer/SDKs/MacOSX10.5.sdk/ ]; then
+    # Build for x86_64 architecture if OS 10.5 SDK is present
     if [ ! -f lib/.libs/libcurl_x86_64.a ]; then
         AlreadyBuilt=0
     fi
 fi
 
-   
 if [ $AlreadyBuilt -ne 0 ]; then
     echo "curl-7.17.1 already built"
     return 0
@@ -151,7 +138,7 @@ export CPPFLAGS=""
 export CFLAGS=""
 export SDKROOT=""
 
-if [ "$DarwinMajorVersion" != "9" ]; then
+if [ ! -d /Developer/SDKs/MacOSX10.5.sdk/ ]; then
     mv -f lib/.libs/libcurl.a lib/.libs/libcurl_i386.a
     mv -f lib/libcurl_ppc.a lib/.libs/
     lipo -create lib/.libs/libcurl_i386.a lib/.libs/libcurl_ppc.a -output lib/.libs/libcurl.a
@@ -160,7 +147,7 @@ if [ "$DarwinMajorVersion" != "9" ]; then
 fi
 
 
-# OS 10.5
+# Build for x86_64 architecture if OS 10.5 SDK is present
 
 mv -f lib/.libs/libcurl.a lib/libcurl_i386.a
 
diff --git a/mac_build/buildjpeg.sh b/mac_build/buildjpeg.sh
index 8dff2598ce..09f66cb5cf 100644
--- a/mac_build/buildjpeg.sh
+++ b/mac_build/buildjpeg.sh
@@ -23,7 +23,7 @@
 # Script to build Macintosh Universal Binary library of jpeg-6b for
 # use in building BOINC.
 #
-# by Charlie Fenton 7/21/06
+# by Charlie Fenton 12/4/07
 #
 ## In Terminal, CD to the jpeg-6b directory.
 ##     cd [path]/jpeg-6b/
@@ -33,11 +33,24 @@
 # the -clean argument will force a full rebuild.
 #
 
+AlreadyBuilt=0
+
 if [ "$1" != "-clean" ]; then
-  if [ -f libjpeg_ppc.a ] && [ -f libjpeg_i386.a ] && [ -f libjpeg.a ]; then
+    if [ -f libjpeg_ppc.a ] && [ -f libjpeg_i386.a ] && [ -f libjpeg.a ]; then
+        AlreadyBuilt=1
+    fi
+fi
+    
+if [ -d /Developer/SDKs/MacOSX10.5.sdk/ ]; then
+    # Build for x86_64 architecture if OS 10.5 SDK is present
+    if [ ! -f libjpeg_x86_64.a ]; then
+        AlreadyBuilt=0
+    fi
+fi
+
+if [ $AlreadyBuilt -ne 0 ]; then
     echo "jpeg-6b already built"
     return 0
-  fi
 fi
 
 export PATH=/usr/local/bin:$PATH
@@ -51,6 +64,7 @@ if [  $? -ne 0 ]; then return 1; fi
 
 rm -f libjpeg_ppc.a
 rm -f libjpeg_i386.a
+rm -f libjpeg_x86_64.a
 rm -f libjpeg.a
 make clean
 
@@ -70,13 +84,53 @@ export SDKROOT="/Developer/SDKs/MacOSX10.4u.sdk"
 ./configure --disable-shared --host=i386
 if [  $? -ne 0 ]; then return 1; fi
 
-export LDFLAGS="-isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386"
+if [ -d /Developer/SDKs/MacOSX10.5.sdk/ ]; then
+    export LDFLAGS="-isysroot /Developer/SDKs/MacOSX10.4u.sdk -L/Developer/SDKs/MacOSX10.4u.sdk/ -L/Developer/SDKs/MacOSX10.5.sdk/usr/lib/ -arch i386"
+else
+    export LDFLAGS="-isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386"
+fi
 export CPPFLAGS="-isysroot /Developer/SDKs/MacOSX10.4u.sdk -arch i386"
 
 make -e
 if [  $? -ne 0 ]; then return 1; fi
 mv libjpeg.a libjpeg_i386.a
-lipo -create libjpeg_i386.a libjpeg_ppc.a -output libjpeg.a
+
+if [ ! -d /Developer/SDKs/MacOSX10.5.sdk/ ]; then
+    lipo -create libjpeg_i386.a libjpeg_ppc.a -output libjpeg.a
+
+    if [  $? -ne 0 ]; then return 1; fi
+
+    export CC="";export CXX=""
+    export LDFLAGS=""
+    export CPPFLAGS=""
+    export SDKROOT=""
+
+    return 0
+fi
+
+# Build for x86_64 architecture if OS 10.5 SDK is present
+make clean
+if [  $? -ne 0 ]; then return 1; fi
+
+export PATH=/usr/local/bin:$PATH
+export CC=/usr/bin/gcc-4.0;export CXX=/usr/bin/g++-4.0
+export LDFLAGS=""
+export CPPFLAGS=""
+export SDKROOT="/Developer/SDKs/MacOSX10.5.sdk"
+
+./configure --disable-shared --host=x86_64
+if [  $? -ne 0 ]; then return 1; fi
+
+export LDFLAGS="-isysroot /Developer/SDKs/MacOSX10.5.sdk -arch x86_64"
+export CPPFLAGS="-isysroot /Developer/SDKs/MacOSX10.5.sdk -arch x86_64"
+
+make -e
+if [  $? -ne 0 ]; then return 1; fi
+
+mv libjpeg.a libjpeg_x86_64.a
+
+
+lipo -create libjpeg_i386.a libjpeg_ppc.a libjpeg_x86_64.a -output libjpeg.a
 
 if [  $? -ne 0 ]; then return 1; fi