I have used every version of Windows produced from 3.1 to XP, then I spent 10 years in the Mac world. About a year ago, the last Mac I had died after running more or less flawlessly for 5 years. I then bought the best system I could afford. I had $350 in the bank at that time, it wasn't a Mac I bought.
I came back to the Windows world through Windows Vista, because I had the choice of buying a machine with Windows, or going without. (Yes, I know that Linux is free, but i could not have bought the same horsepower I did with no OS. Also with the iMac dead, I had no way of downloading Linux. I had to get something I could turn on and use. As for Linux, as soon as Photoshop runs on Linux, I will probably switch to Ubuntu.) Going without was NOT an option.
Last week I upgraded to Windows 7.
I found Vista to be an improvement over what i remembered with XP but overall a big MEH!
So far, I am mostly liking Windows 7. I haven't had any real issues with it, but also haven't had time to really use it and get to know it.
The one thing I miss more than anything else, iLife. I wish that either Apple made iLife for Windows, or there was an alternative that did the same thing. If there is I haven't found it yet. I have been able to find individual apps that do the same things, but it was nice to get everything in one package.
The whole Windows vs Mac thing is so old hat as to be laughable. It really doesn't matter anymore, and I'm not even sure it mattered then. Use what works for you and you like. If your able to get the work and/or enjoyment done,... that's all that matters.