I spent about twelve hours today getting ubuntu up and installed on my new computer and then promptly removing it and installing windows 7.
Although the installation was long and painful (thank you, OCZ), once it was up and going I was very satified with it. It looks much better and works much better than the last time I had tried some form of linux (three years ago). Of course, there is still the constant requirement to go to terminal; although that is fine by me, it is still a major barrier to wide spread adoption.
My decision to remove it and go back to windows came from windows software. This computer being HTPC rather than for gaming, I figured I wouldn't need anything windows specific, but I found out better soon.
A tiny app. Open source even - but only available for windows. And it is the stupidest little thing - all it does is automate downloading anime and updating a website. That one thing killed what otherwise would have been one more box running linux.
I find it all rather humorous. Linux has come a long, long way, but even the smallest "problems" will turn away users in seconds.