If you're going to buy a new computer, PC's wreak less havoc on your wallet, as elephantinc suggested. However, it doesn't sound like you're in the market for a new computer, are you? You're asking whether or not to use bootcamp?

I would say, stick with your current OS since you have PS and others for it. The benefits of Maya on Windows are not enough to justify re-buying your adobe stuff, if there are any benefits. I personally haven't used Maya on OS X much, so can't say for sure.

If you do feel the need to windowsify, I would go with 7 over XP as support will be growing for 7 all the time, and drop off for XP, if you see my point.

Penultimately, since you have 2008, why do feel the need to upgrade? 2008 is more recent than 8.5 which is what is required.

Finally, I don't see why these threads need to degenerate into arguments. Of course, people are entitled to opinions, but we should all keep are preferences open to review, and logically work out the pros and cons on each side.

Hope that gives you some feedback to go on.