H2V does not support WXGA (1280x800 and 1440x900) resolutions. The closest you can get (widescreen) is 1280x720. It's really stupid since 1440x900 is such a common widescreen res (but Hired Gun made a shitty port, so...)

Also, post your specs. If your video card is not good, you won't get good framerates at high settings. Personally, I think high settings are not worth it since the game looks just as good as the Xbox version on low or medium settings, and on high settings, the game only looks a little bit better yet slices your framerate in half.