Yay! One big happy family.
I still have my K1 which is my actual "library". All Kindle books are downloaded to the K1 automatically (those are backed up on Calibre). I keep very few books on the K2 because it's so easy to pull htem from the archive.
Now thanks to DesertGrandma, I have the freebie Dropbox account. I keep all my Calibre books there so
I can even pull the non-Amazon books from the cloud with Whispernet (of course everything is backed up 7 ways from Sunday, just in case).
Congratulations on your new Kindle 2!
Edit: So far I have not been able to download from Dropbox via Whispernet. I aplogize for posting untested information. I'm still going to keep trying.