Unlike past versions of Windows, the Vista upgrade edition requires you to have XP already installed. (That is, you can literally upgrade, but you can't do a clean install).
Hopefully that version of XP doesn't need to be activated, because the upgrade process apparently invalidates your XP key. (Luckily, a workaround has been found to allow a clean install, but it requires installing Vista twice).
I know piracy is a big issue for Microsoft, but there has to be a better way to handle this (and let's be honest, they don't exactly have a good track record on past attempts). Like DRM, these hurdles tend to piss off legimate users more than preventing piracy, because those who are determined to steal their OS will find ways to do so.
I wonder if we'll end up with future operating systems built on microtransactions. You want search? $10. Power management? $5.