What is the full version of the BIOS?
mvktech has revision 4 of the 6800U AGP reference BIOS, and its version is 5.40.02.10.15. Of course, they have a bunch of other versions, too.
I've flashed my 6800GT OC a few times, and would be glad to help for free. You can use the 50 bucks to offset the cost of Oblivion