What OS do you use and why?

For me:

Windows XP Professional.

Why:

I have a few old classic games that work on Windows XP, but not on Vista etc. So I have decided to stick with Windows XP at least for the time being.

via Bleeping Computer Last 20 Posts http://www.bleepingcomputer.com/forums/t/450561/what-os-do-you-use-and-why/