As of two days ago, I have replaced my Windows machine with a shiny black Ubuntu box. Three years ago, when I purchased my Windows Vista laptop (thinking it couldn't be all that bad, HO HO HO WRONG), there were still several desktop applications that I used on a regular basis.
When I decided to upgrade again this year, I took a long, hard look at my desktop usage for a few days.
One desktop application (that runs fine under Wine, by the way), and Chrome. That's it -- my computing life essentially consists of nothing but webapps.
So when it came time to upgrade, I had a simple choice: Windows 7 or Ubuntu. I've long sinced used Ubuntu for my development PC, and I was very comfortable with it. It's got great hardware support and it's fast as hell (my developer machine is specc'd lower than my Windows laptop, yet performs much better).
So, given a choice between two almost identical operating systems in terms of functionality, which one do you choose?
The free one.