I've got XP, and it works for me. I've tried Linux and just left confused. OS X is nice, but can get troublesome sometimes.

What are some other lesser known operating systems?

Also, does anyone know about any nice shells? I'm a fan of LiteStep, it's tough to learn at first but can really beautify your computer. I want to check out some other, lesser known shells. I already know of BB4Win and the other BB's, those are nice but not really what i'm looking for.