XP 64? use or not

Building some computers for my friend and it just hit us we might need 64.

specs are intel core2 quad, p5e asus, 8600gt, with 4(1x4) gigs of ram.

these are for rendering with maya mainly and ive never had a need for 64 with my own computers. should i download, i mean buy, 64 or stick with oldschool xp

>>5
I don't get it.

>>6
So how does this offer better performance than 32bit architecture?

>>7
Ah, that's finally something. Well, sounds as if we won't really benefit from x64 until applications have been revamped to take advantage of these architecture cleanups. And I'm not talking about a quick recompile like they seem to have done with XP 64.