depends on the source of your problems - you haven't said the gfx card you have currently
Most of FF is CPU dependant, if your choppiness doesn't improve when you change GFX settings (lower quality and lower res) then it's probably your CPU. If you see many improvements then it probably is indeed your GFX. Likelihood is that it is a bit of both (CPU and GFX) if your PC is quite old...
You can often tell from comparing netgraph and +showbudget to see what fps you get. Please someone correct me if I'm wrong cause
I can't remember for sure; but if driver time (quoted in miliseconds on +showbudget) is high and the fps is lower than the fps shown in your netgraph then it's your CPU that's dragging. Choppiness is often CPU related I've found and correlates directly with what's being shown in +showbudget.
Could you go 'sv_cheats 1', put '+showbudget' and 'net_graph 3' on, spam a lot (mirvs, pipes, grens) and screenshot.
Aftershok/Squeek do you think we could change +showbudget from cheats in a future patch? I cant see why it is and believe it would be useful to check in multiplayer.