I'm running on a Windows XP because it's the best windows out there, I don't plan on upgrading to Vista because it sucks, and Windows 7 looks better, but I'd still prefer XP. Why? Because it's simple and straight to the point. I don't need fancy transitions and shit, I just need a computer than can access the internet. Seriously. And Macs? The only reason I'd get a Mac is for GarageBand because that's probably the best thing Apple did. Macs are too complected anyways, they're no real explorer that I can view my files easily, there's all these different things and just, ugh! XP is the best so far in my opinion, it's simple and easy to use.
And once again, this is all just my opinion, don't start bitching like "Macs are the best! Shut the fuck up" because you're just wasting my time. I'm starting my opinion, not saying what is true.