The other day I was in my advisor's office and he said "let me show you something you've probably never seen before: a fully legal version of Chinese Windows!".
I don't understand other cultures... Why pirate Windows when you can have Ubuntu for free?
A number of reasons: Everyone else is using windows, you're familiar with windows, all your software runs on windows, and installing Ubuntu requires a lot of downloading when a version of Windows is a cheap disk from a local store.
It's probably more the quality of OpenOffice vs MS Office (and other desktop apps) rather than Ubuntu vs Windows per se.