I don't know a single home user on any OS that is using IE6. My incredibly behind-the-times relatives on Windows 2000 are using Firefox, and any of my XP or newer friends and colleagues are using Firefox or a newer flavor of IE (or even Chrome).
No, the thing holding up IE6 is corporate America. My company has 70 large locations in America, and probably twice that around the glob, together running about 60,000 computers. Only one (very tiny) division of our company is allowed to run anything other than IE6, and that's because they are a Windows Vista technical support group.
The rest of us are forced to use IE6 because most of our applications have been replaced by browser-based 'solutions' like Siebel CRM and the like, using ActiveX and most of which aren't officially supported on newer browsers. It's painful.