Plus the 360 is really compatible with windows, so I don't have to connect anything, to listen to music from my laptop whilst playing a game on the 360. I can do that with movies and pictures too.
the ereader is essentially a virtual book, that is to say, the screen looks like paper, and thus has no back light (no eyestrain). It stores a book electronically, so you can look up words and such, I can also listen to music while reading.