Multiple Power Supply Failures

I have a Gateway 1400, Pentium 4, 1400mhz, 128mgb ram, 40gb HD, Windows ME, purchased 12/00. So far, I have had to replace the power supply on this machine twice in less than a year. I suppose it could just be a run of bad luck but I suspect thereis something else going on with this machine. Does anyone have any idea as to what could be the cause of repetitive power supply failures?