I dislike the entire Windows OS. I use Linux as my main OS, and sometimes Apple. Unfortunately, since my schools network runs on Windows, I am forced to use it everyday :( I try to avoid it as much as I can, though.
One reason I don't like Windows is that it is not Open Source, meaning that the source code that makes up the Windows Operating System is not open to anyone who wants to edit or view it. With Linux, the source code is free and open, so you can change the kernel to fit your needs.
Rant over :D