I fail to see what's wrong with Gnome. It lacks the flashy effects of KDE, but otherwise is quite adequate. I prefer it precisely because there's less **** to turn off. A vanilla Gnome setup is usually adequate for me.
If I wanted a pretty desktop, I'd use a Mac. If I wanted to have to turnoff a crapload of stupid features, I'd use Windows more.
It's true that Windows is the only platform for hardcore gamers. Mac OS might pick up now Apple has moved to Intel chips, but I think it's unlikely unless Vista sucks a lot. Macs are for people who use their computer for work only, and don't want to play games, install miscellaneous crap off the Internet, or spend time fixing problems with the machine.
The OS you use is mostly dependant on two things: what you use the computer for and how much you can afford to spend.
Gamers and people who need compatibility use Windows. People who like to tinker, don't want to fork out for software, or are just plain sick of Microsoft use Linux. People who use their machine to produce stuff, can afford professional software to do that production, and don't need a wide range of apps tend towards Macs, although this will change with Intel Inside...
