Not worth doing anything to that system it is way to out of date any thing you put in it will not give much of a boost in performance. According to the tech docs it is running with DDR1 RAM and AGP graphics which is so far outdated that even the fastest processor and GPU that you could find for it will still be far too slow for modern software and games time for a new platform. If on a tight budget you can build an AMD system for as little as 300 if you do some bargain hunting.
Good Luck