Hi my freind just intsalled a Vooddoo 3 2000 agp in to this computer

OS: Windows 98 se
CPU: PII 350mhz
RAM: 398mb

With the Voodoo 3 installed he is unable to rasie the resolution past
640 * 480 and is having problems playing games (old win98 games).

Any help would be greatly apreciated.