Generally almost all programs in x64 windows installed in folder "C:\Program Files (x86)". So you need to change start.bat accordingly. Here the example of run.bat for client:
I will work for both x32 and x64 editions of windows@echo off
set P="%ProgramFiles(x86)% "
if %P%==" " (
"%ProgramFiles%\Java\jre6\bin\java.exe" -Xmx120m -cp bin;lib/clientlibs.jar client 0 live english game0) else (
"%ProgramFiles(x86)%\Java\jre6\bin\java.exe" -Xmx120m -cp bin;lib/clientlibs.jar client 0 live english game0)
pause