So-Low,
So what frame rate should you be getting?

Just for grins, change the window to framed and make it 800 x 600, see if the frame rate changes. Or it could just be a setting in your graphics card. I usually find that if I can make it change, I can make it better.

I remember some posts back that some people have made some changes to the graphics settings in their graphics controllers. I don't know what settings they are, but you may want to do some back searches on frame rates to see what comes up. (sorry if you have already done so).
Scott