Most people know that Windows 7 comes in three primary editions (Home Premium, Professional, and Ultimate), but did you know that there is also a fourth primary edition called Windows 7 Starter?
Windows Starter Edition Evolution!
The important thing to know is that Windows 7 Starter Edition is intended for use on netbooks only. You can't get it on a standard PC (and in most cases you wouldn't want to). It may still be offered as an option on netbook models that are still available.
Windows 7 Starter is a significantly stripped down version of Windows 7. Here are some of the things that are missing, taken from a Microsoft blog post:
One feature that will be missed the most is the ability to change the look of your desktop. Don't like the wallpaper? Then you'll have to live with what's included. Note that you also can't watch DVDs. But if you can live without those features and want the stability and strong performance of Windows 7, it's an option worth considering.