For Windows 7, once you upgrade to a higher edition, you really can’t revert back without some serious registry hacking, etc. This really shouldn’t be a big issue, but it’s good to know. Also, for Windows 7, you can upgrade from Home Premium to Ultimate without having to upgrade to Professional first. You can basically skip editions.
Click on Start, then type in anytime upgrade into the search box and click on Windows Anytime Upgrade to get started. Note that Windows Ultimate will not have this feature since it’s at the highest edition already.
Now just follow the instructions to upgrade to a new edition of Windows 7. First, click on Go online to choose the edition of Windows 7 that’s best for you.
In the same dialog, you’ll get a list of the different versions along with a nice table of features for each. This is also a great way to compare the different versions of Windows 7 and actually see what the differences are.
You can also click on the tabs across the top to see the features of each version separately. Once you buy a new version and have an upgrade key, click on Enter an upgrade key.
That’s pretty much it! After you enter your key, Microsoft will confirm it and all the new features of the higher edition will be available immediately! No need to download anything or install any extra software. Enjoy!