1. What OS are you using? (Dual-boot? with what?)
Windows on the terminal, ubuntu on the server I ssh into constantly.
2. Why do you use that(these) OS(s)?
I don't own own the end computers I use, one day, but for now I control the servers in the basement and the network. I use ubuntu because its what worked for me. I liked gentoo but my hardware is too old for the compiling (and if you use precompiled binaries on gentoo you might as well not use gentoo).
3. What advantages/disadvantages does it have?
I use web-based things for email and everything, only need PuTTY and I can live. =) The disadvantage is that I can't install whatever I want on the computers (well, I can... but I have to be more careful not to mess them up).
4. Related websites?
http://microsoft.com
http://ubuntu.com
http://www.chiark.greenend.org.uk/~sgtatham/putty/
http://en.wikipedia.org/wiki/Secure_Shell
5. What should an OS consist of?
A web browser and ssh client. Optionally some sort of graphics and the ability to use a mouse. I could live entirely
CLI. I should see how long I could go entirely CLI... I don't have a good way to view images =P I'm thinking image->ascii art.. I'll play with that later.