Avoid Windows Vista Upgrade Disks
With Windows Vista now available in stores, you might be thinking about upgrading your existing system or completely upgrading to a new system. In general, I'm leaning toward keeping all existing systems running Windows XP and only putting Vista on new machines, but that's primarily because I'm at least a year overdue for upgrades already. If you do decide to brave the upgrade path from XP to Vista, whatever you do, don't buy an upgrade version of Windows Vista. You'll be sorry later. In the past when you upgraded from one version of Windows to the next generation, you could do a clean install with the new OS and simply insert the old CD as proof you'd purchased the previous version. This time around, Microsoft makes things more difficult.
If you upgrade from Windows XP to Windows Vista, the upgrade CD requires XP to be installed before you install Vista. This means if you wipe your system, you'll have to install XP and then install Vista for a total of two complete operating system installs where one would have been sufficient.