The typical PC user uses a web browser, an office suite and videogames. With Chrome you have an excellent web browser regardless of OS; LibreOffice is fine for many users and it's interface is similar to that of Office pre-Ribbon, which many appreciate. Games have been a painful issue, but with browser-based games and Valve porting to Linux it's getting really better.
I believe it's a matter of time until users begin questioning the Microsoft tax when they can get a useful OS sans viruses and malware for free.