Coming from UNIX it does servers & business stuff well, network, & Internet.
As a desktop WS: office programs, pictures, audio, video, web browsing, etc.
Games it does OpenGL games: Quakes, Doom, Unreal T., & lots of others.
DirectX it hasn't been real successful at, YET. WineX & a new one are trying.
Linux also has games written for it, most of them are rather simple though.
There's also Mame which runs the games that are on arcade machines.
GameBoy emulators, PlayStation emulators, & maybe a few others I'm sure.
Games are definately Linux's soft spot, I'd be rid of WinBlows except for that.
The legendary stability of Linux over Win. is true, but each has advantages.
For simple to setup & use you might try: Knoppix, Ubuntu, Linspire, & Mepis.
Some are live CD (run from CD & may install to HD), & some HD install only.

Hope this helps, if you have more Qs, that's what this place is for!