Running Mac Mini Duo, WinXP with all upgrades and no Bootcamp. When scrolling in Word documents or in the web browser, it seems as though the screen is spit down the middle vertically and that both sides of the scroll are trying to keep up with each other. Once I have finished scrolling the page comes together again and everything looks fine. This doesn't happen on the Mac side only on the Windows side.
I have noticed that too on my 20" iMac Core Duo with 2G. I think the Parallels video implementation is not very fast.