Paladine: I'm using a 7850 (just recently got a second) and on average the best I can seem to hit is about 300MH/z average @ 1,010 MHz core with peaks up to 350MH/s (the nvidia card you have wont get much better sadly) so that may give you some sort of average to look at where you should be.
This is on windows 7 x64 using GUI Miner -v 1 -w 256 -f 1 (I tried w 128 and f 0 as well)
right now I keep having my miner say connection problems, you wouldn't happen to be having that issue as well would you?
Garbaek: I may look in to that myself thanks