As a computer scientist, Linux is interesting for its Unix roots and as a source of code to look at for ideas and solutions to problems.
As a developer, there is no substitute for Visual Studio 2008, and the beta 2010 has me only using 2008 when I need to create 2008 .sln files to send files to other people not using the 2010 beta.
Also as a developer, C# is one of the best languages ever created. Hands down. If you are dissing it, you obviously haven't used it or you are working on projects close to the metal. Even for those projects though, this might prove you wrong.
As a political scientist, I wonder about the overt socialist nature of the GPL and wonder if the same problems that brought down socialist governments will bring down or restrict the adoption of socialist software.
As a gamer, I have absolutely no use for Linux. People who say they use their consoles are only getting 1/3rd of the possible gaming experience. Windows computers are the best gaming machines known to man. If you disagree with this, you obviously haven't tried PC gaming.
As just an end-user, I hate the Ubuntu interface. KDE is much more to my liking. Even still, the Linux directory structure is confusing and downright stupid. This makes doing simple file tasks hard.
Under Windows I know that my programs will always be under C:\Program Files. Under linux, the executable itself will be in one place, the startup script in a completely different place, and other files will be god knows where. Not only that, but between different distributions, sure there's the same basic directories, but they put the program files in different directories than other distributions. Its crazy.
Finally, as a tech geek with an eye on the future, I wonder whether Linux's chances at widespread non-server/embedded will survive the era of cloud computing. You can be guaranteed that Microsoft will have a cloud ecosystem and that linux will not be a part of that. Microsoft has the money to fund a massive cloud ecosystem. Where will linux get that money from to build and run a similar (knocked-off) cloud ecosystem to give linux users all the great things that Windows user will enjoy? Food for though.