The game is horribly buggy on the PC, avoid at all costs until it's patched.
First off, if you have Windows XP SP3, don't even bother. Numerous reports are flooding in that the game will not run on SP3 due to some glitched OS version check. Windows XP SP2 and Windows Vista appear unaffected.
There's a much bigger problem though; the game checks how much RAM your video card has and will not let you set the resolution higher than 1280x800 if you have anything less than a 512mb graphics card. The problem is, it checks every card in you system, not just the primary one. If any of your cards have less than 512mb of video RAM, it will limit you to 1280x800.
So here I am with a GTX260 896mb and an 8400GS 256mb (used for my 3rd monitor), the game sees the 8400GS and caps my resolution to 1280x800 even though it's running on the GTX260...
Aw man that bites. Have you tried forcing your desired res in an INI file?