Anyone have computer-buying advice?

My computer died last night. She was over nine years old and still on her original mousepad, keyboard, and monitor. She was vastly outdated years ago, but I kept plugging along with her. Today I am using a computer at the local college to get online, though that I can't do that all the time. It just isn't feasible. Anyway, maybe I can squeeze together around $500 and buy a low-end replacement from Best Buy. A new computer in the cheapest price range would probably be capable of much more than my ancient girl was. But I need advice!

( Questions inside )