What Cota said. Virtualization for the most part is more applicable for business-related use. We use VMWare on our servers all the time where I work. Except for the very few and far between techno-nerds who want to play with multiple OS's on their PC, virtualization will be totally lost on your mainstream PC user.
Also appears to me MS is trying to take out a quite a few 3rd party developers with Windows 8.
Enterprise (at least for windows 7) is just a volume licensing version of Ultimate. The same is mostly true for Vista (enterprise loses the media center though)... so for what its worth bakape's comment is still valid.