Upgrade the current computer, or buy a new one?

[PDX_David]

If it is more sluggish than normal you might check it for spyware using adaware, spybot etc...

More RAM is a great idea. Seems 512 is about as low as you want to be with WinXP.

If the video is sluggish you might want to look in to a new videocard. Not sure what you have now, might even be intergrated video since you said it was a low money PC. That could be using your RAM too.

Really doesn't sound like you need a new PC to me. Couple things might make it better than new.