You must've bought this Converter from Alpha Bid
http://cgi.ebay.com/Serial-RS232-to-...QQcmdZViewItem

If it is correct, the specs on this page says that this converter is not compatible with the VAG cable that Alpha sells.

But anyway, your cable is good to work with any laptop with a serial port. My laptop don't have serial ports, just like yours, so thats why I bought a USB cable instead.
Sell the cable, and keep the converter, its a very handy tool, does'nt matter if it dont work with VAG software.
[:-]

no thats not it, they dont have the one they sent me listed now.
The one I have is just a plug no cable on it.