Well if you want an AMD system, someone else will have to compile the parts for you. Since I do not use them, I do not know which chipset is the least buggy and what not.
Bruce, I would suggest buying a new computer, your P3 machine is quite dated, and most of the parts would have to be replaced. My reccomendation is to sell the computer for what you can, and buy a new one. I can give you a workable setup, just specify how much money you are willing to spend, and if you will build it yourself.
The System I am going to get is about 1350, but it is very top of the line and includes a moniter in the price. You could probably get a good gaming computer for 800-1500. It depends on whether or not you would build it yourself