Right now I'm using Windows because an Ubuntu driver update has left my Wifi card useless. It'll probably be fixed within a few days, but till then I'm stuck using Windows XP. As I was hunting around for apps to make XP just a little more bearable, I happened across allSnap. It's a neat little app that sits in your system tray and makes all the window edges "snap", like in Gnome, XFCE or KDE.
This means, you can tile your desktop with windows and slide them around on each other without worrying about aligning them precisely. It's a bit hard to explain, but it makes window management a ton easier. Check it out if you're interested in usability and efficiency.