If you havent already done so, I highly recommend checking out the WorldWide Telescope, yes, yes, Google-did-it-first with Google sky in Google Earth, but seriously WWT is more awesome, its got lots and lots of guided tours by astronomers and its generally much prettier.

Its an amazing tool for learning about stuff in the universe, and I'm sort-of bummed it hasnt gotten more attention.

I'd say this is just about the coolest thing MS has released, and its completely free too. Its still in Beta, so there are some bugs in there, but its still pretty awesome.