Also, I am also considering going for the latest Beta OS over 1.4 if that's the final OS. I want the best OS available regardless of if it's complete or not. Any recommendations on where and how to install that joint?? 
Most of the guys who frequent the forums use the latest beta, you get two files one for the voice and one for the OS, there is a thread pinned to the top with the files in
http://forum.davesmithinstruments.com/index.php/topic,586.0.htmlboth files are attached to the bottom of the first post
the LFO sync is broken but most of the main bugs are fixed in the latest beta, its pretty good, defo download Elektron C6 its a much better program, i uploaded some sound files to my Tempest with midiOX and they were all buggy, when i uploaded them through C6 they worked perfectly.
edit - I don't think you have to upgrade the voice first, but you do have to upgrade them both, there is also some tips on if your OS didn't install properly in the beta post, worth a read. Try C6 and if that doesn't work try a different midi out if you have a hub or an different soundcard or something. Good luck again!