I have no idea why this works better for me than Scrollbar hidden / hide scrollbars totally. I just copied it from comments on it. Your mileage may vary. This causes the scrollwheel to stop working in XP _and_ makes it so that searching with '/' doesn't jump to the results. That's pretty terrible!

The addon has an option to drag exactly as the scrollbar does when you grab any part of the webpage.

Vimperator users can just use ^U,^D, jkhl to replace using the scrollbar.