Using Windows 98 Second Edition, the mouse pointer isn't as smooth as it was on XP, its a Microsoft Intelli Point Optical, with all the latest drivers form the Microsoft website. It's hard to explain, but if i was to move the mouse left in a straight line, it would make small jibbers up and down. It's essential that i get it work smooth (and straight) as i use Flash MX and other presentation/animation programs.
Are there any incompatability issues to do with the mouse and Win98 that the manual/manufacturers website mention? The only other thing I can think of is if you have a modem there could be an IRQ conflict between the mouse & modem.