This post went from silly to oh dear god why did someone ever start it...
People use OS's for what they want, some people just buy a PC it does the job out of a tin. Some people buy a Mac, it does what it does.
Linux = for those that like to play and deal with Servers.
I use a mac for design, video, audio etc when i want, use windows, XP,Vista, 7 depending if i use another laptop, i'm at work or on my home machine. Both OS's do what they are good at. simple as really, i Have MS qualification but oh no. i use a MAC aswell... reason being... it does what i need it for better than a PC can.