Thanks for posting my exact same situation, OP. In my case, I have a single core Socket 939 Opteron 148 and an x800xt (actually, a Connect3D x800 GTO unlocked to 16 pipes and overclocked to x800xt speeds).
Unreal Tournament (both the Original and 2004) is by far my favorite game, and the only reason I'm interested in upgrading is to be able to play UT3. It's too bad that Epic hasn't released any benchmarking data for the game yet (as far as I know), but I guess we'll find out in a couple weeks when the demo's released.
What kinds of settings are you hoping to play the game on? I'd like to play at 1024 x 768 with at least medium detail and 40 FPS minimum.
I wonder what would happen if I kept my single core Opteron and merely added an x1950 Pro.
What happens if x1950 Pros are available for $130 shipped, hard-to-find x1950xt for $175 shipped, and 8800 GTS for $240 shipped (lets assume some price drops in November)? Which one would you choose? If the x1950 Pro can be shown to cut the mustard for that game while the x1950xt can provide good performance and the 8800 GTS would provide excellent performance, which one would you choose?
Does anyone know if UT3 will require a Shader Model 3.0 card? Bioshock seems to require it and it uses the same engine, but will UT3 require it? I'm guessing it wouldn't simply because Epic is supposed to be known for its scaleability.
Thanks for the links, Russian Sensation.