The music sharing isn’t what you’re thinking. You can play music from any iTunes library running on your LAN. For example, when a coworker fired up iTunes for Windows, he saw the complete libraries of both me and my other mac-using coworker. He can’t copy, burn or iPod the songs (without a utility like iLeech) but it’ll stream it to him while he’s on the network.
As for seeing a Powerbook inside-out, check out these pictures 🙂 If you go to an Apple Store/CompUSA you can actually see a lot of the hardware if you remove the keyboard (pull the tabs next to esc and F12) and they usually leave /Applications/Utilities/Terminal.app so you can try the Unix stuff out.
I like OS X (and hate OS 9) because it’s the one platform that will let me run my Unixy stuff as well as Microsoft Office (and other commercial apps) with minimal hassle. The rest of the cool stuff is just icing on the cake. If that’s something that interests you (and WiFi range isn’t of utmost concern) you would do well to try out a powerbook.