Put linux on it and keep using it, nothing wrong with it.
This post brought to you from a p100 system with 16mb ram !!
Put the right software and setup on an old machine and they work great, no your not going to play cutting edge games, but web surfing, web servers, game servers like quake, and p2p is no problem.Ive got one box with 320gb of storage running linux on a p100, no monitor,no keybrd,no mouse, just a network card........it makes a fine fileserver.