anybody know computers? help!

[_paralyzed_]

now I've got nothing, a blank screen when it turns on, and I need to unplug it to turn it off. If I put in the restore cd it will run it, but unsuccessfully. I've never been inside a computer case and wouldn't know what I was looking at if I opened it. I'm going to have to bring it somewhere. Is it worth the cost of diagnosis and repair? Its only 256ram 1.4ghz 60gbhd, I'm thinking I could probably upgrade for what I would fix it for, but I have no idea and it worked fine for e-baying and talking here, which is all I do on a computer. Thanks again for any advice