Because I'm forced to consider a video card upgrade to my beast anyway (going, going, almost gone), I thought I'd ask for any recomendation by the Aces High POWERS-THAT-BE

. Given my current config and assuming all background tweaks being equal, what components should I upgrade (and what kind of additional bang for the buck do I get for each) to significantly improve gaming performance on AH. Consider that when running properly, I have never achieved a frame rate over 59 with this setup, though it is usually fairly consistant.
I guess what I'm really asking is, which possible upgrade (faster cpu, going to 2GB RAM, or installing a newer, AGP video card like ATI X850 XT or Nvidia 7800 GS) gives the most increase in performance, comparatively, and is it worth it to do more than one of these at this time?
Current specs
Computer: Monarch Hornet Pro
Motherboard: Asus P4P800-VM (AGP)
Power: 265W
CPU: P4-3.0Ghz
RAM: 1GB (2x512) Crucial
HD: 2 Western Digital 36GB Raptors
Sound: Creative SB Audigy Platinum Pro ZS
CD/DVD: Plextor PS-708A
Video: Asus Radeon 9600 XT 128MB
Monitor: 17" NEC CRT @ 1024x768
Thanks for any input.