please comment on cpu 32 bit or 64 bit

please help me ,
comment on postgresql (8.x.x) performance on cpu AMD, INTEL
and why i should use 32 bit or 64 cpu ? (what the performance difference)

thank you

_________________________________________________________________
Express yourself instantly with MSN Messenger! Download today it's FREE!
http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/