Generally the best-behaved Mac knockoffs have something similar to the following:
Core 2 Duo/Quad
Gigabyte P35 mobo (Gigabytes just seem to fare better, though Asus does OK)
Some ram (doesn't matter)
Hard disks, preferably SATA and in AHCI mode.
Best results seem to be with G92-based Nvidia cards and 3870/3850 ATI cards. The 9600GT is a particularly troublesome booger last I was reading.
So CPU no, mobo no, graphics no.
You have roughly 0% chance of getting a really representative OSX experience on your hardware. It'd be hacked ten ways from Sunday and probably buggy even then.
I'd say it's not a good idea at all.
Behemoth - media server
Galactica - test lab server
Falling Outside the Normal Moral Constraints - MBP 15
Donnager - M4800 DTR
Rocinante - E5530 testing machine
Saratoga, Ticonderoga, BunkerHill - the Hydra desktop PC-thing.