I just keep my data on an OS that doesn't require regular reinstalls

I've come to the point where I'm convinced that people are just doing some messed up stuff to their computers. I've definitely been on this installation of my OS since I put this computer together over a year and a half ago, and that's because I was switching OS hard disks. I know 1.5 years isn't a terribly long time and nothing to brag about, but I see no signs that this install is going down the tubes any time soon.

I'd be interested in seeing how often people reformat Win2K installs. Before I put my roommate's box together, he formatted and installed Win98 about every 5 months at least. Since then he hasn't reinstalled once.