1. Insert the Vista DVD into the DVD drive while your current Windows Vista is running.
WARNING: Do not boot the computer and run the Vista installation DVD from boot. A upgrade install will not work this way.

2. Click on Install Now to start the upgrade. (See screenshot below)
NOTE: If AutoPlay does not load the Vista setup screen, then open your DVD drive in Computer and click on the Setup file.

3. If you want Vista to check for updates during the installation, then click on that to select it. (See screenshot below)
NOTE: It will install faster if you select Do not get the latest updates for installation. You can install them later through Windows Update.

4. Do not type in a product key. (See screenshot below)
WARNING: If you do type in the same activated product key that you already have installed, then you can end up in Reduced Functionality Mode.

5. Leave the Automatically activate Windows when I'm online box unchecked.

6. Click on Next.

7. Click on the No button for the Do you want to enter your product key now? prompt. (See screenshot below)

8. Select which edition of Vista you have. (See screenshot below)

9. Check the I have selected the edition of Windows that I purchased box and click on Next. (See screenshot below)

10. Click on the Upgrade option. (See screenshot below)

11. Follow any instructions left until Vista is through installing and has rebooted to the final welcome screen on the Vista desktop.

12. Remove the Vista installation DVD.

13. Now all you need to do is to activate Vista.

A) Right click on Computer (Start Menu) and click on Properties, or open the Control Panel (Classic View) and click on the System icon.

B) Scroll down a bit and click on: Activate Windows Now. (See screenshot below)