My question may sound stupid or inappropriate for this site in which case I apologize before hand. This thing has bothered me for quiet some time so please correct me if there is anything inappropriate:

I have been using Ubuntu for past 1 year and I know how awesome it is and in what terms is it better than windows.But around 2 weeks ago some of my friends asked me to show them something on Ubuntu or tell something about Ubuntu that makes people prefer it over windows. I tried to convince them by telling things like its open-source, that most of the super-computers run on Linux, that its unaffected by virus and other stuff but they seemed unconvinced. Maybe what they we looking for was some mind-boggling feature which only Ubuntu (Linux) has. Since that day I have been thinking but yet don't have anything that will show them the true powers of Linux.

Please suggest your response to such a situation as it troubles me that I am not able to explain them one thing that I myself believe in. Thank you.

PS : I am not looking for a theoretical answer but would like to hear of one such application which it and only it provides.