A few things to suggest:
-Get the Latest Video Drivers from ATI
-Put the game in 98/Me Compatibility mode and disable Visual Themes and Desktop Composition.
-Radeon 9800 is pretty Ancient as far as Video Cards go, you might want to consider upgrading. (Either Vid Card or the Whole System. Though System upgrade would definitely get you more mileage, I also realize it may not be feasible depending on your situation.)