Look here at this new review for the 320mb 8800GTS:
Techreport's numbers show the same thing:
The 8800GTX doesn't really get smacked down until 2560x with filtering. I shouldn't need to upgrade this card using a lowly 1680x monitor for quite a while.
Under MCE 2005 I was seeing 45-60FPS in dense grass in Oblivion running HDR 4 x AA and 16 x AF. I haven't installed and tested it yet for Vista. I was using CaptNKill's distant LOD pak and a custom config file. I use to hate those areas with older graphics cards.
The cities were another place for slow downs in the past and my OCed C2D took care of that. 52 FPS for a low with max viewing distances in Bravil and 89 FPS at the same area if I use them at 60% towards the right. I am talking about actor, object, grass, tree etc.
Check the driver section of the forums. I believe a beta driver was indeed released for SLi. It did have crappy performance though.