A quick rundown on a motherboard beeping function, 1 short beep = fine, 2 short beeps = something like not so fine but still ok, 1 long beep = something else etc... It is different for every motherboard, best if you find your model (open your pc and look at the motherboard for make + model, example:
http://www.ultrabios.com/graphics/motherboard. jpg ) and research it.
If your computer is constantly beeping and won't load up its probably a hardware problem inside (such as a ram card is lose, or a cable has become disconnected). If it is passing the BIOS starting part (to windows load up screen) you can try reinstalling windows. It is more likely to be a hardware problem though. If you end up reinstalling windows you could potentially lose all your files but your pc will be faster (make sure you have your windowsxp cd key and drivers!).
If you tell us when it 'won't work' or stops working it would be a help. Good luck, I'll keep an eye on the post.