According to the EULA, if you have XP installed, you have to re-purchase
Windows XP Upgradeable Edition ($399), and install it, in addition to the
Upgrade version of Vista, if you want to retain any of your old XP data and
configuration. You are also required to agree to publish a web site using
Vista Upgrade Announcement Tool, and you're not allowed to say anything
negative about the upgrade experience, only positive things. Read it, it's
right there in the EULA!! On page 335!!
Jon