RoboTimbo
Hostile Nanobacon
I sent my two Word docs with The Hobbit and The Lord of the Rings to my Kindle yesterday. Both converted very well (except for the table of contents) and are marvelous.
How about any maps or other graphics? You might try saving the files as web pages and either send them to be converted or use Calibre. I've had better success that way. Word docs or rtf don't seem to let graphics or tables of contents convert properly.