Yamaha DTXpress/DTXplorer/DTXtreme

hi guys i have owned a dtx express IV for about a year now and sadly enough am only using it for bare bones practise n bashing the hell out of it really, i have dreams of being able to play it properly but lack time and i suppose willpower to get my head into it properly,i have a very short attention span!, 
i assume that i can hook the dtx unit up to my computer via the midi?
and can then upload new samples/sounds onto it, is that a correct assumption, i shall need to read a lot more into this group, its great to see so many people all with this kit, and look forward to becoming more accustomed to my kit with all your help thanks. john