I don't know if you want that Dell Media Express. The only way to get it is to use it on the preinstalled system. They do not supply a setup for it in any form. If you want to use the funky buttons at the front to control sh*t, that's the only way.
Edit: If you want the funky buttons to LAUNCH the player, that the only way. The buttons will still control the DVD software that came with the system if you install Media Direct and CyberStink PeeWeeDVD.