I have Windows Vista and have installed the USB drivers, and rebooted (twice).  Vista recognizes that the Droid X is connected by USB, but only sees four of the ~20 folders on the memory card, but not the one I want to move the file to. 

So I figure I'll copy is to one of those folders and then move it on the Droid once it's there, but the copy to the Droid did not work.