ok, I got an old Cisco Aironet 350 PCMCIA wlan card and thanks to the original great software uploaded at MG, mobile internet works now, under Os9.1 and also in OsX 10.4.8..not bad, a liitle slow at 11 Mbit/s but what the heck.
I tried a full day to get a Proxim Orinoco gold, but a newer, Atheros based one and it was just plain incompatible.
Another cheap card, a pcmcia Siemens Gigaset 45 was instantly recognised as AE with full 54 Mbit/s under Tiger.