I run Windows 7, and adore it. My mother has a MacBook Pro and I use that too when I work for her. I'm not a huge fan. It works and all, but it has its issues. (My mother bought the Mac thinking, "Omg, they have like, no problems!!!" and her eyes about bugged out of her head when she realized the thing drops the signal from her wireless mouse like it's its goddamn job, and messes with her internet connection constantly, AND freezes up. Heh... Yeah, Mom, now you're a Mac. Welcome!)
Basically, so far the sleekness doesn't make up for the fact that every time I try to do something, I encounter at least one problem I wouldn't on a PC.
For example, I was trying to set her up with a blog. And I was trying to find really good, FREE desktop blogging software. There were a bunch of great options to choose from for Windows. For Mac? Hahahaha, not so much. There was NOTHING. Crap like that annoys the hell out of me.