Vista - games crashing

i use vista 64 bit for gaming as well as xp pro. i have 2 hard drives. one for vista and one for xp. i can play any game i want on xp pro flawlessly. but almost any game freezes on vista. i have tried many clean installs and everything i can think of to stop this from happening. i really like vista but for gaming it has been a horrid experience for me on vista. i have an ati 4870 1 gig gfx card,Q9550 quad core 2.83 cpu with xigmatech cooling. 750 watt psu corsair and 4 gigs of ddr2 1066 ram. now let me clarify i have tried many ideas from an over clocking forum. being i can run anything fine on xp with no problems tells me it is not hardware but a software issue. but it is figuring out what software is causing the hard freezing on vista hdd during gaming has me dumbfounded. seems L4D runs fine but bf2 and cod4 hard freeze resulting in a hard reset. i thought it was punkbuster, but it does it in non PB servers. now i do have a wireless card i use for gaming, some think it is the wireless driver, but it works fine and i can use it fine for xp. xp never gives me any headaches on anything. but vista doesnot seem to like online gaming and sometimes locks on when using online updating for drivers/software. ????????

first off XP is way more stable than vista (i love vista but it is the truth).

i also would lean to it being the wireless card, as i have no issue playing any games on my rig with Vista x64.

can you hook up a wired connection to the rig to see if it still freezes with that connection or no?

At this point in time i don't but if this keeps up i might just go ahead and find a way to make it happen. my bedroom is upstairs and has no way of Ethernet.(why i even bothered using wireless) but if this persists i might just buy a long cable and see if it corrects the problem