Open-sourced tools

I read Mark's post about open-sourced softwares and especially LINUX. These days, I am hearing about this famous LINUX more than ever and I would really like to know why the hell is it supposed to be ''better'' ?? What are the advantages of using it? For what kind of users is it useful to install such a program? Is it faster? Is it hard to install? Are there any disadvantages of using it? Thanks for answering !!

The accessibility of one's identity via internet is starting to freak me out. I'm about to close my facebook page : Maybe not that much .. because as a real facebook addict I couldn't REALLY think about doing this.. but at least I think I'll take off a couple of compromising picture .. that I definitely don't want any future employer to see ! The article about Online Identity Management made me realise how many employers were actually searching on the web to find their future employees..-