Your system is also similar to mine...it deserves a 9800Pro instead of a 9600XT. I have playable framerates at 1024x768 with graphics turned to high on Farcry, HL2, etc.
Again, just make sure you don't buy a cheaper OEM, SE or LE model of the 9800Pro. Look at the specs of the card carefully, they should tell you the memory and core clocks. Then go to google and read a 9800Pro review which will also tell you the standard memory and core clocks. If they match, buy it and then hopefully the card comes as advertised.