There's a guy in Germany selling a Tech 2 interface with free software.
You can find him on e-bay . co . uk. search for Tech II, under cards.
It sells for £35 UK pounds.
It reads and resets all codes (including air bag), software is not 100%, most of it is in English, some in Hungarian.
Lots of the guys in the UK have this kit and are reasonably pleased with it.
The Catera is only the USA version of the Opel.
If anyone is interested, have a look at our Omega (Catera) site in the UK,
www.omegaowners.com.