My housemate re-installed Windows on my laptop with an Ubuntu partition for me for Christmas. Ubuntu is a version of Linux, which is a free-software version of Unix. I like Linux, but I'm finding that I'm not using it as much as I hoped, for two reasons.
First, I do a lot of collaborative writing, and most people use Microsoft Word. I actually kind of like Microsoft Word because of the "track changes" function. When someone else is in charge of the paper, it's nice to send them a copy in which they can see what you have changed. I also grade student papers this way. Unfortunately, the free software version of Word, OpenOffice, does not have this feature (while we're on the subject, I don't think I can do this with LaTeX either). Either that or I have not figured out how to do it so that it looks as good.
Second, one of the main things I do on my laptop is read PDFs. But when I read, I like to make occasional notes and mostly highlight. For this I use Adobe Acrobat Pro, which is incredibly expensive, but my school has a group discount so I get it very cheaply. I have not found a good Linux program that can highlight PDFs for me.
One thing I do enjoy doing on Linux is writing in LaTeX. I like the ease of getting to the command line, I like using Emacs in a Linux environment.
Currently, at home, I have Windows, Linux, iPhone OS, and Mac OS, and I use all four pretty regularly.
Pictured: Linus Torvalds, creator of Linux. Thank Linus!