I don’t know what else is as slow as Vista. However, upon installing XP Pro, Vista Ultimate, and a few other selected OSes on my MacBook Pro via VMWare Fusion (great effing product, by the way), I realized what everyone had been complaining about so much.
Vista really is DRM masquerading as an operating system. And a poor OS at that. At least I can sleep at night knowing that m DVI port is free and open, unlike the poor sods with new MacBooks and MacBook Pros that have the Mini-DisplayPort who must deal with HDCP incompatibilities. Boo fail.