I'm getting vertical artifacts with a 7500. These appear on the DOS bootup screen(s) but with drivers installed don't appear in normal Windows use. However, on overlays they're back - big time. Coloured vertical digital trash. (this is also visible on any second screen connected VGA or video) I've tried a variety of drivers with results varying from awful to diabolical. Am I missing something or is the card duff? Any advice gratefully received.