with that flunky 9600pro, dont run ANY AA or AF. And the max resolution I would try is 1024x768 with that card. It just doesnt have the horsepower to run the game at meduim-to-high settings.
I am running the game on two machines, one at work and one at home.
My home machine it runs flawlessly with everything turned up to max. Specs are -
Athlon 64 X2 4600+ (Manchester core)
2gb Mushkin 2-2-2 special DDR RAM
2 6800 Ultras in SLI
Sound Blaster audigy 2 zs
2x 400 gb hard drives, 2x 250gb hard drives, 1 WD Raptor 10000 RPM hard drive (36 gb, C drive).
Dual Samsung 172x LCD monitors, 17"
OCZ 520w PSU
Like I said everything works great on that machine. The machine I use at the work LAN parties though, thats a different story. Specs -
Abit IC7 Max 3 motherboard
Intel Pentium 4 Extreme Edition 3.2
Radeon 9800XT
1 gig Kingston Hyper-X
2 WD Raptors in Raid 0
I have to run everything at medium on that 9800XT, and the resolution at 1280x1024, just to make it playable. No AA or AF.
Honestly, my tip is to turn off AA and AF completely, and run everything at medium. Also set the draw distance no higher than 80%. If you still get choppiness, drop the resolution down to 800x600.