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

>>8
The only revamping required _is_ a quick recompile. If an OS is written correctly, the compiler (and a few hundred lines of assembler for booting and stuff that's impossible in C) is the only thing that needs to change for different instruction sets.

Ignore that, this is Microsoft we're talking about. I'm sure you'll have to pay through the nose for an upgrade.