Today, I'm working for a small retail company in Madrid, Spain: Ten people, running Windows, Linux, and Mac OS. All of us are using OpenOffice. It already was that way when I came here a year ago. Until now, I heard nobody even mentioning our office software. And these people are not "computer geeks" by any measure; we sell clothes.
I guess it is the reliance on Excel macros, which are not compatible with OpenOffice Calc, that prevents lots of companies from switching. If you don't depend on any of those, I honestly see no advantages in using MS Office.