Yamaha DTXpress/DTXplorer/DTXtreme

hi...

if someone could please help to clear this up I would appreciate it-

I know that the DTXpress doesn't have sample RAM, so I cannot load my 
own samples into it.  If I create sounds on the computer, is there NO 
way to get those sounds into the DTXpress?  When one does hook the 
DTXpress to the computer, what do you do with it?  Is it only to 
trigger a computer through the DTXpress?
I guess I'm just not sure why the DTXpress has the ability to connect 
to a computer if you can't load anything from the DTXpress to or from 
the computer...

thanks, and sorry if this seems like a dumb question!

-eddie