Locking up

Hi, im kinda new to forums to please bear with me.

I bought a Gateway arround 4 years or so ago , it worked fine for the first 6 months then all of a sudden it started locking up when i attempted to put world of warcraft on it . I sent it back to gateway and they claimed to have rebuilt all of the hardware components in it , yet it did the exact same thing every time i got it back and continued to get worse to the point where i could not even boot the cpu. Im not sure if its the Graphics card, altho i have changed it out atleast twice, still doing the same thing. I finally got the techs from Circuit City to come out and replace the Processor but it continues to do the same thing, ive also changed out the ram, im afraid its either the hard drive or the mother board, i dont want to sink anymore money into this pos unless i have to. The gateway model is 614GE ... please help, i have a 1700 dollar paperweight that i'd love to use for a gaming system.

Thanks,
Criss