At first, some news outlets reported that Upgrade versions of Vista would require the user to enter an XP key -- the long combination of letters and numbers you need to install XP in the first place. Then, we were told you didn't need the key, but instead would be required to insert an XP disk during the Vista install. Earlier this week, some sites reported that the requirement was that XP had to be installed on your PC, and that a clean install -- installing Vista only on a reformatted disk -- would be impossible.

Don't feel bad if you still don't know which of the Upgrade proof policies above is the real one -- few outside Microsoft do. (In fact, none of them is correct.)

Microsoft created this confusion by failing to tell anyone what the proof requirement would be for using an Upgrade version of Vista.

Meanwhile, the Upgrade versions are poison:

- Windows power users know that if you want Windows to work well over the long haul, it helps to reformat and perform a clean install once in a while. The Upgrade version requires you to install both XP/2000 and Vista every time, doubling the already massive amount of time it takes to do a reformat/reinstall.