i suppose that i am not explaining myself very well because of all of the confusion. i don't mean just plugging in to one computer and then another...of course that is what they are all about. i merely wanted to know whether i could intall all of my software on the external HD and use it as a start up disk on each of the various computers. cipher (who understood me) replied that he thought it would be fine. misha (also seemed to understand) replied that it could potentially cause problems if certain prefs or something are only on one computer. at least it is worth a try. i thank everyone for their comments.<br><br>[color:blue] -sean</font color=blue>