I learned from a mistake, never under all cirsumstances ever try to update the BIOS if your system running stable and smooth!! The only solution to improve your graphic performance, is to upgrade your current GPU.
Currently I'm running Crysis on 8800GTS 640MB with 1280x1024 res and 4xAA, the game run smoothly with E8400 factory clock, 4GB Memory, XP-64bit. I was planning to upgrade with 9800GX2 in the very short time.
Again, the only reason to update the BIOS if you find out that your system is running creepy all the sudden or the old BIOS doesn't support a new peripherals like CPU or memory for instance because the bus frequency is different on the new one. So, check with your Mobo manufacture, sometimes you need to update 1.xx BIOS version first before updating the 2.xx version.
I was having serious performance issues with skyrim for the past 3 weeks, and having tried all other avenues mods etc., I updated my bios from A09 to A11 yesterday using an official dell update. The game performance is vastly improved. I never realised that it would make such a difference,