in the meantime I gave the new rt2x00 driver a second try. It seems that it has improved since my first try, as it now works on my notebook, including WPA encryption.
This time I didn't try to set the prarameters manually in /etc/network/interfaces - I instead use the network-manager with "managed" set to "true" in the nm config file, i.e. I now have an almost empty interfaces file (because I have cable and wireless connection at the same time and the network-manager automagically sets the route). It works like a charme.
You were lucky. I did not have such fortune...
I tried rt61 and rt73.
Something wlan0 and wmaster0 were presented as the output of iwconfig.
Since I am a noob, I will not be able to do more...