man, i use cracked windows XP game edition 2007, have no antivirus, and old kainozoic comp with mezozoic drivers and tons of installed warez. and everything is ok (except lags)
if theres no cpu overheating (or any other chip temperature problem - for example i had an overheating and short curuit problem with some details on my videocard - it burned with open flame 2 times! but still works) and other 3D games played OK, well... what if to try other OS (like XP) in virtual machine? it is neither difficult for you nor for your system.
i know, that advice does not sounds well, but it is not a big problem, for example in VirtualPC. (which included in new release of Total Commander Power User).
or maybe local guru will help you more with it (maybe 64bit Windows 7 is not good for gzdoom - who knows)
