Until last week I used Win2K on my primary home machine. I got a new machine and it had XP on it. I only run Win2K in virtual machines at the office, because most people are still running Win2K there and I need to help them out.
My employer has not moved to Windows XP, so even brand new machines are reinstalled with Windows 2000. There is a significant investment in custom-built internal applications which are known to work in W2K, so I can understand their reluctance to move to XP or Vista unless/until they are forced to by MS.
At home I have a VMWare image running Windows 2000 to check my sites with IE, if that counts. I suspect I'll have to upgrade when IE7 comes out if that won't work with 2000. (Other than that I don't run Windows at all).