Ok, just as a follow-up, in case somebody would come here hoping to find a solution for the problem I described here:

Well, I haven't found a solution yet, but I found a workaround: I installed the Ndiswrapper v0.7 together with the Windows XP driver from the Toshiba support website, instead of using Intel's official Linux driver to get the Centrino Pro2100 wireless network card on my Toshiba TECRA M1to work under Knoppix 3.3. And it is working quite well: I have successfully connected my iMac via it's Airport wireless network card to my Tecra M1via it's Centrino Pro2100 wireless network card using an Ad-hoc network!

And with Intel's official linux drivers the ad-hoc network feature is far from being released yet

Enjoy.