Este artigo da Microsoft, Atualizando? Coisas a serem consideradas , permitem isso e todos os caminhos de migração:
"Personalizado" é definido como:
A custom installation erases everything on your hard drive. So you'll need to back up all your files, photos, music, and settings on an external hard drive or on CDs or DVDs and then transfer them back to your PC after you install Windows 7. You'll also need to reinstall all your programs from their original installation disks.