Rarely. Been win7 at home for years now. At work just finalized the upgrade a little over a month ago. Now the only XP machines are mostly laptops that seem to randomly pop up, or are machines that are used for label printing and don't go on the internet. XP machines are now banned from our network, and I more or less refuse to support them now as I've got better things to do. Have had far less work orders put in since moving all our 360 pc's to win7, and upgrading along the way.
If local government can find a way to do it, I'm sure bigger operations can do the same.