one thing to note..
easiest way as said above is get the shoestring cable and do away with the handset altogether.. the handset is a painful way to go. see Link:
http://www.store.shoestringastronomy...roducts_eq.htm
going the way you are going - theres plenty that can go wrong even though you are seeing some results.
1) make sure you have a compatible usb to serial - they are all very different and most dont work. theres plenty of data on these on a simple search.
2)make sure you put your handset in PC mode. Not entirely sure the menu on the handset but this maybe where your stuck at.
\Ben