Another option is mobi2html from MobiPerl
. There are binaries for Windows (you don't need to install Perl to run MobiPerl on Windows). The command line is similar to mobi2oeb. First copy mobi2html into your current directory (not necessary if it is already in your command path) and then issue the command:
mobi2html ebookname.mobi ebookname
This won't work if the ebook uses MobiPocket's high compression option though.