Same here, I loved using Windows XP, I was able to install most games in there. Vista was ok, but the current one that I'm using, Windows 7, doesn't run most of the games that I attempted to install in there. So my preference will always be XP. I think I should reinstall that OS again when I get a copy.
The newer OS options are so much more smooth than past iterations. Windows 7 and Windows 8 feature such vast performance improvements and stability improvements over XP. In fact, even Windows 8 is a noticeable improvement over Windows 7 in terms of performance and features. I've heard great things about the past couple Mac OS versions, too.
