Make sure your eclipse.inieclipse.ini file includes the following lines.
-vm
C:\path\to\64bit\java\bin\javaw.exe
My eclipse.inieclipse.ini for example:
-startup
plugins/org.eclipse.equinox.launcher_1.1.1.R36x_v20101122_1400.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.2.R36x_v20101222
-product
org.eclipse.epp.package.java.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
256M
-showsplash
org.eclipse.platform
-vm
C:\Program Files\Java\jdk1.6.0_32\bin\javaw.exe
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-vmargs
-Dosgi.requiredJavaVersion=1.5
-Xms40m
-Xmx512m
Use OS and Eclipse both 64 bit or both 32 bit keep same and config eclipse.inieclipse.ini.
Your eclipse.inieclipse.ini file can be found in your eclipse foldercan be found in your eclipse folder.