Well, since you seem to have went cheap on just about everything, it could be one of three things, if not all. XION...hmm. That's such an off brand I've never even heard of it. I would speculate that it is indeed the PSU, since the 450 watt XION PSU at newegg is only $30USD. And none of their 5 PSU's have any reviews. When I heard you got 2gb of ram for $180, that also leaves me wondering. And to top it off, a samsung hard drive. I first suggest you get yourself a real PSU, such as
this one. Then, I would suggest you dump the RAM you have now (2gb is complete and total overkill if you are not building a state of the art PC) and get
this instead. Last thing left to do, is replace that samsung hard drive with
this one. If you do all this, and you still have that problem, I will buy you a custom built alienware rig with a custom paint job of your choice. Oh, one other thing, do NOT get a Thermaltake PSU. They are known to be faulty. If you cant get the one by PCP&W that I suggested, get one by Antec such as
this one.