Nope, absolutely correct, which is why I haven't touched it in over 3 years of having it.
Took the plunge today though, sat down and read some of the guides and just followed them point by point. Razza77's guide was good on M3Cutters/E46Zone.
I've got the BMTechnic cable - BMTechnic have folded now though
Massive shame as they had some clever people who made everything into one easily package, that installed everything automatically and it works on Windows 7 perfectly.
There must be something out there that has replaced BMTechnic as the preferred cable, but I would definitely get one. I have diagnosed so much, so quickly with the cable and INPA/DIS and now I know how to do some basic coding. All for £30!