People over at the guru3d forums are claiming some wildly increased framerates when using this new 84.56 beta driver. I myself am using it now, and I too have seen some signinficant in-game performance from Oblivion as well as in benchmarks (3dmark 06 went fro 6040 to 6275 just with the driver change) from the 84.21 and 84.43 drivers I had been using with my 7900gt.
Bear in mind that this is a "beta" driver, and your experience may vary, but most people are really liking what this has done. BTW, it is WHQL certified.
Download link for the 84.56 x32 driver (winXp/2000): http://downloads.guru3d.com/download.php?det=1385
Download link for the 84.56 x64 driver (64 bit winXP): http://downloads.guru3d.com/download.php?det=1386
Here's the thread over at guru3d where they are discussing this driver's performance: http://forums.guru3d.com/showthread.php?t=180744
Let us know how it works for you. :)
I got it downloading as I type this... Will come back later with my results of this new driver. pe@ce