You might want to try the BookCreator 2.8 beta
You can import your Word doc into BookCreator and create LIT/MOBI/ePUB/LRF and IMP from within BookCreator (BookCreator is a MS Word templare with Macros optimized for creating eBooks. (this tool also used calibre). The LIT file calibre creates is the best I've seen even better than commercial eBooks.
If that is not an option I'd recommend you just create a MOBI file from "MobiPocket Creator". calibre's MOBI are not as good as those created with MobiPocket Creator
Import the MOBI file to calibre and create your files from there.
You'll have to run "any2LIT" from the command line since LIT creation is not inclueded in the GUI yet.
Or you can create everyting form the command line once you've created your MOBI file from MobiPocket Creator.