Unfortunately there are conflicting requirements on the kernel-version (by ndiswrapper for running Wireless-card and by the RTAI realtime operating system). I'll leave this problem for later.

I bought the PCAN interface, which is a buffered interface between a CAN-bus and a USB-port. Peak-systems are also offering an obfuscated-source driver (see driver-page).

The next step is a difficult one for me: I'll have to connect microcontrollers to a CAN-bus (and to sensors and actors of course).

So far I tried an Infineon-C167, which was at hand. I gave up, because there is no properly documented gcc-backend.

I'll have to try Atmel AVR next. It seems to have a strong developer-base. So I feel safer to go in this direction.