Yamaha DTXpress/DTXplorer/DTXtreme

I'm about to get a dtxpress and of course will be hooking it up to my 
pc.  My question is, what do i need exactly?  Can i just get a cable 
and connect it to the joystick/midi plug on my soundcard and connect 
the other end to the midi plug on the dtxpress?  if so, what exactly 
will this accomplish?  i've been reading that people are connecting 
their pc's to external midi devices and then to the dtxpress, i.e. 
there's a "MIDI" device in-between the dtxpress and the PC.  Is there 
any advantage to using the TO HOST connector over the midi 
connectors? please help!
-chris.