Unix (Mac OS X, Linux, etc.) because it's easy, powerful and complete
(not because Micro$oft is bad):

Every paragraph starts with a sentence that is either not true anymore, or has never been true at all

“no applications”
You might only need the free Mozilla and Open Office.
The rest is probably in this long, but incomplete Linux application list or this list of software for the Mac. Fink enables Linux software on the Mac.
And if you ever really absolutely need MS Windows there's always containers, emulators, dual boot and your neighbor’s computer.

“no support”
The huge workforce of developers around the globe are developing and improving programs and giving support on it. Both commercial and free, both closed and open source.

“no compatibility with MS Windows”
MS Windows networking and MS Office documents are quite standard already, Exchange and more is also getting there.

“it’s difficult”
Unix has powerful Graphical User Interfaces. Knoppix needs no install. Mac OS X is the most user-friendly OS in the world. Lindows looks like MS Windows.
The Command Line Interface is there as an extra powertool.

“I’d break it”
When you don't login as an administrator, but as a normal user you can’t break it. It's harder to have it break by itself, cause Unixes are less vulnerable to viruses than MS Windows.

“too big a step”
I would taste Linux with Knoppix from CD and maybe use it as my "computer on a CD+pendrive". Later go to a dualboot Windows/Linux install, probably removing Windows after a while. If i had the money i'd buy an iBook (you need a Mac to run Mac OS X).