Before running the benchmarks we played the games at both resolutions. To play at the native resolution of 1280x800 we had to switch the layout to 16:10 so the 1280x800 resolution would show as an option in both games. On both games this resolution yielded somewhat choppy framerates with very apparent slowdowns.
However, there was a noticeable improvement playing at 800x600. Drop the resolution and image quality settings a bit further, and game performance obviously would improve even more.