Not really the place to ask this I know, sorry

but I'm sure someone here will know...
My PC has a 64-bit processor. I bought the PC over 2 years ago, and wanted it to be somewhat future-proof (didn't know then whether 64-bit and/or Vista would take-off or flop).
I'm still running Windows XP (I haven't heard many good things about Vista) and I'm happy with it, except it bothers me that only "half" (not literally) of my CPU's potential is being realised. Would upgrading to Vista 64-bit actually improve the performance of 32-bit apps such as SH3, or make no difference?
Cheers
OLC