The version of Emplode you should be using, just to be clear, is 2.0 final. That should also be the version of firmware on your car player (check it from the About menu), and if it's not, that could be the root of your problem.
The USB conneciton issue might simply be
this, except that the older USB driver should in theory work on win2k. Worth a shot to install the new driver.
The RS-232 cable absolutely MUST BE a 9-pin null-modem cable. Not a straight-through cable. That's what you should be asking for as you phone up computer stores.