With your graphics card that score looks pretty good. Maybe an OC on it would increase a bit, but not too much.
I mean when I had a 5200FX i got 909 in 3dmark03 (05 wouldn't even work) and with my 6800GT I get 11500 or something! And 5263 in 05!
Try running aquamark as well, that's a decent one.
The most importanty thing is the way your games play. download FRAPS: http://www.fraps.com/
and then bench the games your playing. That'll also allow you to tweek the games to get the right mix of FPS and Picture quality. Benchmarks are a bit synthetic sometimes!
Oh yeah, like I said: OC;ing will help a bit, but you'll never really see a huge difference in the results, it won't be absolutely huge.
3DMark and Aquamark are, as I said, synthetic benchmarks that are designed in collabration with the card manufactorers and CPU makers. (my opinions only and I will accept no responsibility for them being taken as libel! ) )
3Dmark05 keeps getting further support from nVidia as it uses DX9.c to its limits. They do show some nice touches but as I said, its all about real-time game experience!