Rant,
Well, MediaJukebox needs RealPlayer if you want to play real files. If you're only interested in mp3, mpc, ogg, ape or vqf
you don't need Real Player.
On my system I only have MediaJukebox installed ( no Wmediaplayer, no real, no winamp) and I can enjoy my collection of roughly 5000 mp3, ape, mpc.
If you let MediaJukebox scan your HDD, and you have, by mistake

, some 'Real' files in your path, MJB will try to get the necessary software in order to play it (i.e. realplayer). What you should do is to uncheck all real files extensions (.ra, .rm...) in the import file type box.
Have a nice day.