Você deve ser capaz de fazer apenas uma atualização in-loco para o Windows 8.1 Pro ...
Em MS: Caminhos de atualização para Windows 8 e Windows 8.1
You can upgrade to Windows 8.1 Pro and keep Windows settings, personal files, and applications from the following Windows operating system editions:
- Windows 8
- Windows 8 Pro
- Windows 8 Pro with Media Center
- Windows 8.1
Em seguida, adquira e instale o pacote do Media Center:
De Adicionar o Windows 8.1 Pro Pack ou o Windows 8.1 Media Center Pack à sua edição do Windows 8.1 :
Swipe in from the right edge of the screen, and then tap Search.
(If you're using a mouse, point to the upper-right corner of the screen, and then click Search.)
Enter add features in the search box, and then tap or click Settings.
Tap or click Add features to Windows 8.1 and then do one of the following:
• If you need to purchase a product key, tap or click I want to buy a product key online.
Follow the steps to purchase and enter a product key.
• If you already have a product key, tap or click I already have a product key.
Enter your product key and click Next.
Read the license terms, select the check box to accept the license terms, and then click Add features.