Here's my 2 cents (pen'orth). I recently upgraded my PC with a new mobo and cpu. I was lazy and just added my system hardrive to the mobo without doing a reinstall. The graphics from my GeForce 2 were OK but there was a jerk in the action every 1 second.

I later decided to do a clean install of Windows 98SE and the problem disappeared. FWIW. HTH