Did you say your using the stock drivers that come with your graphics card?
The "stock" drivers are not truly drivers, and your missing out on years of optimization that has been done by Nvidia. I could possibly see where your coming from if you have an ATI card, but AFAIK Nvidia is usually great with driver updates.
Update your drivers man, I guarantee that will fix your problem. That would also explain why the patch has made your game have graphical issues, it may have worked with v1.0 of Fallout 3, but as patches come out new issues are introduced and Nvidia therefore puts out driver updates to fix them.