Took a look at the games I already had and ran a few of their benchmarks. Just finished playing some STALKER and the fps/visuals increase makes me very happy

although the game is still true to STALKER buggyness and crashed out.
Anyway, some benchmarks:
3D Mark Vantage
9800GX2 as I ran them
9800GX2 multi-GPU on
SLI GTX280
Dirt2
9800GX2 as I ran them: min 42.5, average 51.3
9800GX2 multi-GPU on: min 36.8, average 47.9
SLI GTX280: min 71.3, average 107.5
Far Cry 2
9800GX2 as I ran them: min 28.86, max 70.19, average 37.31
9800GX2 multi-GPU on: min 31.02, max 112.32, average 73.43
SLI GTX280: min 85.57, max 178.75, average 113.93
Pretty pleased with the results. Happy at being able to turn the AA + details up and still enjoy increased fps.
Before:
The cards:
After:
Also worth noting that the temps are considerably better than I was hoping for. My 9800GX2 was peaking at 100C (think it is in dire need of having the heatsink cleaned out) whereas the hotter one of the two 280s is peaking at 75C. I ordered another fan mount for my case thinking I was going to need the extra intake but turns out it would have been fine.