Have you tried asking SDL directly? If not, why? They should be more than happy to assist you, considering that you're trying to buy something from them.
SDL Trados 2006 is Trados 7.5 (=the version you're using).
Versions prior to that, like 7.1 and 7.0, are different from SDL Trados 2006.
Actually, I tried asking them directly by filling out a form, but they never got back to me ...