I've been using Mac for 20 years. Used to be the operationg systems and ways of performing common tasks were fairly different between Macs and PCs, but they've evolved to where there are more similarities than differences now.
As a longtime Mac user, I finally went over to the dark side and bought a PC too, so now I'm "bilingual". But I have to say, Vista seems ok to me. It's annoying when it constantly asks permission to perform a task, but otherwise I have no problems with it-except the fact that Vista doesn't like Adobe Acrobat!
You'll like Macs...they're great computers.