well, im thinking of buying parallels, but i was wondering a question or two about it. 1. After i buy parallels, will i still need to buy a version of windows (vista, xp, etc) to install over parallels, or does windows come with parallels 2. Does having 2 os's stored on one computer slow down the speed of it, and how much space does it take up. i have the base end iMac.