You need 64 bit as soon as you have more than 3 gigs of RAM (32 bits can address up to 4 GB nominally, but because of a well-known limitation of 32 bit Windows, nearly 1 GB of the address space is wasted on other things, so 3.x GB tops). And there are gaming rigs (not including my comp BTW) that have 8 gigs of RAM, which doesn't sound too oversized, now, does it? (Well, I'd say no more oversized than 1.5 gigs of video RAM, Kouen
).