I don't know about all that SLI stuff- but I've got some tweaks that really smoothed out the game for me, without any loss of image quality-
First off, make sure you download the the new 84.24 nVidia driver - it gives a massive boost in performance in Oblivion over previous drivers
Right, go into my documents/my games/oblivion/ and find the oblivion.ini file.
There is an option which controls the grass thickness - which is set too high really, as if you have thinner grass you can get a higher FPS or bump up the grass distance to compensate (which looks much better)
"iMinGrassSize=120" - It'll be set to 80 initially. If you're really struggling set it to 160 or something, but at 120 you won't see any graphical reduction.
If you have one gig of RAM, you can stop stuttering by doubling the RAM settings to the following-
uInterior Cell Buffer=6
uExterior Cell Buffer=77 (this might already be higher, if so leave it)
iPreloadSizeLimit=52428800 (You must change this number if you change the cell buffers)
I got about 5-10 FPS more by doing this - which made a big difference, making the lowest FPS I ever encounter about 25-30fps rather than about 15-20.