Diagnostic code reader for laptop

I've just bought a diagnostic adaptor for my laptop off Ebay. Does anyone have experience (good or bad) with these? I know that Ebay stuff can be frowned upon by forum members, but I have not really had any bad experiences so I thought I'd try one on the basis that if it works once it will have paid for itself...........

The unit has been bought without software, or at least they don't mention it too much so I assume not. However, I am aware that some of the VAGCOM software is available as freeware or shareware. My question is - Which is best for my 1999 1800 20 valve GTI?

Incidentally, I paid just under £10 for the device and it's on it's way from Hong Kong. I've seen many of these for sale both in the UK and the Far East, but they mostly share the same photo so I can only assume they are pretty well all from over there!

I bought one off ebay, also came from Hong Kong and it works perfectly, the disk it cam with was broken but you can download software from the internet. Only small problem I had was setting up my laptop as the device only works off a certain comm port, once I found how to change the name of one of the USB ports it worked perfectly. In order to get really technical you will need to register the software, the unregisted version does give you a good idea what the problem is though.