I heard that there was a high-resolution mod for this. Is it easy to install? I assume this game would be installed under Steam.
Pretty simple. You download the file, put it in the install directory, and then change the .ini file to the various settings you want (1-4 for AA level, type of anti-aliasing, etc.). The game still isn't super pretty, but it fixes the framerate problem and makes it look nicer.
It installs through Steam but requires both Steam and GFWL.