i'm typing on a MacBook Pro now because i hate Vista so much.
I was always a Windows girl, and i thought Mac people were silly and snooty. I had always used Windows machines, and got an XP laptop when i went to college and loved that machine to death. It lasted 3 years and then the motherboard started to go, so I figured I'd upgrade to a new machine and the new operating system (this was in April - Vista came out about 3 months prior).
I work at Best Buy, so I got the advice of all of our computer guys, picked out my laptop, and was very excited...for about half an hour. Although my computer had excellent specs (WAY MORE than recommended for Vista) and I had our Geek Squad guys tweak it to run faster, Vista was nothing but slow, buggy, and frustrating. It would close programs randomly, freeze, and completely restart without warning, and my computer always sounded like it was a jet engine about to take off, even when it was just sitting, closed, not being used. It really freaked my roommate out, because it would randomly start making noises, even when I hadn't been in the apartment for hours.
Vista is a very passive program, meaning it runs a lot of processes in the background, so it's a memory hog even when it's idle (which is why it would start making noise even when I wasn't home). Try to multitask, and I was screwed, even thought my computer's specs were EXCELLENT.
Add the slowness on top of the bugs (which I couldn't get rid of, no matter how much troubleshooting and update-downloading I did), and I just couldn't take it any more after 6 months. I'm very computer literate, and I just couldn't make Vista work for me.
I also absolutely hated Office 2007, I found it completely non-intuitive and frustrating.
I love my MacBook Pro, and I do my best to avoid as many Microsoft programs as possible since my experience with Vista. I have Office for Mac, but I only use it when I know I'll have to open the file on a non-Mac in the future. Other than that, it's iWork for me.