M80

Im playing the CM demo, and when playing the game, the top portion of the screen (sky,etc.)is flickering and graphics appear to smear & studder,but only on the top quarter of the screen. Also,in the mess of flickers and smudges,I can see my desktop icons appear through the top of the screen as if it were somewhat transparent. I have all the latest drivers and soforth. Ive tried numerous tweaks in my control panel/display to resolve the problem. I think this is a great game but Im afraid to buy it because of this. I have the diamond viper 2 S3 2000 video card/p2400/win 98/160mb ram/sb live. Any suggestions? Thanx