All of the Vista Operating System products are all on one disc. It is the product key information that activates the Vista product you've purchased. If you eventually would like to upgrade to a different Vista OS, Vista makes changing the product key a simple task, here's how:

1. Go to Start>> Control Panel>> System.
2. At the bottom of the System applet, you'll see a link titled: "Change product key". Click this link.
3. Click Next, then in the resulting window, enter your new product key ID information.
4. Click OK.