I've been playing around with beos. (Finally figured out what I was doing wrong to install it)
It's actually a pretty cool operating system. Extremely light-weight and boot fast. I timed it on my computer (1.2ghz cpu & 256mb ram) and it took less than 30 seconds, from the moment you push the power button, to the time you actually have a usable system. Windows XP takes somewhere around 1 minute and linux takes about 2.5 minutes.
BeOS comes bundled with just about everything you would need for an os. It has about a dozen games, document processing, software development, web server, a few cool screensavers, image manipulation and effects, video editor (haven't used it yet), 3d modeler, media player for audio and video.
BeOS can be networked with other computers, but I haven't figured out how, and since I don't have internet at home, I haven't researched it at all. With that said, I haven't attempted to connect to the internet either, although it should be possible and maybe even very simple.
The gui is very simple and easy to understand. I bet even my grandma could figure it out in a few minutes.
There's also plenty of programs you can download from bebits.com if you aren't happy with the pre-installed stuff.
Here's the links to the os downloads:
http://www.bebits.com/app/2680http://www.beosmaxfiles.org/
