When users were upgrading to Windows XP, the procedure was that users could simply insert their old Windows 98 or Windows 2000 CD at the appropriate time during a clean install without the need for the old OS to be installed at the time. However, Microsoft has decided to change this for Vista, and now requires a fully installed and activated version of your old OS already on the machine. This comes as an attempt to prevent illegal use of upgrade CDs, but could be inconvenient and time consuming when the time comes to reinstall. The new procedure for a reinstall is as follows:

• Install your old copy of Windows XP
• Activate it either online or over the phone
• Install Vista