From what I have seen of Calibre, it looks to be a pretty good tool. I would also like to figure out how to use it to better effect. Most of my reading on the NOOK will be side-loaded public domain books on the SD card and library books. I think the NOOK will be a good device once I get past the startup pains. But the startup pains have been severe so far.
Using the NOOK will require using both Calibre and ADE because ADE does not present a way to sideload a book the SD card, and Calibre does not handle any DRM books.
One thing that I didn't point out in my previous rant is that B&N applies their software upgrades automatically if your device is connected to the wireless. Some of the complaints on the Adobe forum were that the broken 1.2.1 update was applied behind the scenes, and then suddenly people could not read the books they had bought. The fix for the problem involves wiping out your entire collection and starting over from scratch. One poster said that he had to go re-shelve all of his books after a reset because B&N does not preserve that information when downloading the books from the B&N store.
From a customer relations point of view, that really stinks.
As an eReader, once I got it working, the NOOK is nicely done.