x86 is for all 32 bit OS's and x64 for all 64 bit systems...
It failed on my 32bit win 7 system but worked like a charm on my xp box...so I'm not sure if this is 100% right. Of course it could be *my* machine that failed. Honestly this stuff is above my pay grade, I'm lucky I got it to work at all.
Yeah, I gathered that many in this thread doesn't quite understand what x86 and x64 stand for...that being said, you probably didn't run as administrator on your 32 bit Win7 system....