Well I can't tell you how many FPS you'll get. It's been a long time since I ran 256. I ran 512 for a couple of years. I've been running a gig for about 4 months now.
512 is definitely going to help a lot. A gig is on the edge. It helps some, but not as much from 256 to 512. A gig really makes my CD burners crank though.
Get some good cas 2.0 RAM as well. I run Hyper X & think it's great RAM, myself.
Dazzle them with Brilliance, or Baffle them with BS! :wink: