hey trey,
it could be a hardware failure indeed. check out
www.majorgeeks.com and download memtest86 from the memory section. put the program on a cd and then bootup with it.
then memtest86 will begin testing out your ram for any errors. make sure to let the program run for a minimum of 10passes and see if memtest detects any errors with your ram.
you said that you replaced your power supply with a spare one. i know the power supply is 500watts but is it generic? i recommend good brands such as enermax, antec, and pc powercooling. they make really good power supplies.