I installed all the options. Since it co-exists with mobi-terrible-support-pocket-reader on my machine I created a seperate folder for books and I copy my books that I send to my phone and open in readm to the library folder, then move them to the books folder. I then turn off scanning for things I don't need. Depending on where you are you may need to mess w/ the 'code page' settings or whatever, but to make a long story short....ReadM is easy and works great.
Alternately the base version of mobi(see above) is available and a desktop version of the software to make compatible books is also available (I believe the home user stuff is free). They just haven't figured out that t-mo US firmware doesn't have the right encoding to display books correctly encoded w/o a bunch of square boxes, no matter what I set or how many times I email customer support (these are books I bought so I have a really low opinion of the company). They also have no mac converter, although I think they had an OS 9 one that probably would run under classic, but they don't have it up anywhere.