"If Windows was the underdog and UNIX ruled the world"
You're joking right? What do you think business runs on? Most banks use AIX, Solaris and Linux (probably in that order), most telecoms networks run on HPUX, most large engineering companies (I'm thinking Airbus and the like) use Solaris or HPUX. Windows has only ever lived on the desktop and as desktop support back ends (for example Exchange). I really shouldn't need to point out that the majority of the internet infrastructure runs on various UNIX and Linux variants, too.
UNIX security is sufficient for most purposes. If you wish to run a browser as a different user, you can; then as you describe, your files are kept safe. Likewise, assigning different users to different groups with access to their own unique parts of the system is ... as easy as assigning users to groups.
Also, regarding running 'setup.exe' and rebooting. Try Ubuntu - it even finds the correct drivers for you.
Each to their own. Fischer Price Windows 7 for people who need their hand holding, Mac OSX for those who know what they're doing and just want to get on with it, Linux (and UNIX) for people who work in IT, Amiga for people with a passion! We don't want to dumb everything down to the same level!
Just my 2p.
