It says in the review lol. Same as yours (ish).
Looking at the scores he got, his min FPS was 22 on the XFX 8800GTS. And thats under a c2d oced. My best suggestion would be to turn down the settings a little so it dosn't drop. Google the Oblivion tweek commads aswell, as theres hundrends of options you dont get given.
This may seem like defeting the point of gettting the 8800, but ive said it over and over. Oblivion isnt an FPS orentaied (sp?) game. And even turning down the settings a little it will still be stunning.
Also there is an Nvidia driver written specificly for Oblivion somewhere, although i dont know if it supports the 8 seires.