Save your money. Incremental upgrades are going to give you minor improvements, at best. When you're ready, you should consider a proc/mobo/memory/videocard upgrade, since as another poster pointed out, the nicest and most cost-effective videocards aren't going to play with an AGP board.

Your board is going to give you very little room to improve your proc, and a new proc will likely require new RAM as well as a new mobo.

I'm sitting tight. Not gonna spend a dime on my PC until I can't stand it anymore, and then I'm going to replace the whole shebang. My home-brew PC is over 3 years old, so I'm gritting my teeth and sweating a lot. No more upgrades! None! Not so much as a new fan bay! Nada, nothing! I will endure the torments of low frame rates and the fires of degrading system performance, and I will not weep.