While I happen to like Windows 7, my machine is old and needs to stick with XP Pro for the time being.
Whenever I have the where-with-all (money), then I will upgrade.
Right now though, XP works superbly for all of the programs that I use and there's no genuine advantage (other than "It's New!") to be obtained with an OS upgrade.
Besides, I want to be one of those people who are going to hold Microsoft to their word regarding supporting it until 2014.