I use the program Readerware and I am very satisfied with it. If I remember correctly from a brief trial of Book Collector a few years ago, Readerware may not be as visually appealing, but it does what it is supposed to do and it does it very well. You simply input an ISBN or a group of ISBN,s, tell the program which databases to search, and it will find your book and the necessary information. You can also use a bar coder to input your books, but I have no experience with that feature.
ReaderwareEdit: I just noticed from the Readerware site that they are offering all of their products at a 15% discount until December 31, 2008.