Well first, find out if you have a Nvidia or Ati (graphics) card.
Right click on your desktop, select settings, and it should tell you
.
If you have an ATI card, get the latest drivers from here :
https://support.ati.com/ics/support/...ge&folderID=27
And if you have a Nvidia card, get the latest drivers here :
http://www.nvidia.com/object/winxp_2k_84.21.html
All this applies if you have WindowsXP, you can choose your own here :
http://www.nvidia.com/content/drivers/drivers.asp
I hope this fixes your problems, I always had problems with my nova games, uninstalling, deleting my folder and re-installing always fixed it, so GL!