Check out the following link:
http://www.pfranc.com/cables/index.shtml
In the upper left box is everything you might need, from a pFranc e2PLUG connector with a bare cable, to one with a bluetooth transmitter and auto adapter for the eTrex H. There is also the USB solution you have asked for. None of the other cables linked in earlier posts here will work with an eTrex H.
That link ^^^ is genius, thanks very much