Youc an’t go wrong with Calibre. It is free and comes with versions of Mac, Windows and linux.  Talk about features.  What a slick piece of software.  ”convert between numerous formats: it will convert CBZ, CBR, CBC, CHM, EPUB, FB2, HTML, LIT, LRF, MOBI, ODT, PDF, PRC, PDB, PML, RB, RTF, TCR, and TXT to various formats including EPUB as used by the iPad. The obvious choice would be to save in RTF and convert to EPUB.”  Thanks Rodger Wilmut1 for the suggestion!