epub is basically html in a zip file.
Open the epub book in something like winzip or what ever you would open a .zip file with, and extract the files to a directory.
When you do this you will see a bunch of html files, all you have to do is double click one and it opens in windows explorer.
select all the text displayed, copy and paste it to a word document, repeat for each file in order that is in the directory, save the file under the name you want.
Wahla ... epub to doc =)