I believe the orinoco driver doesn't support WPA/WPA2.
Not sure which chipset it is - could be Prism2, in which case you
_may_ be able to switch to the hostap driver - which also isnt ideal.
The other option is to use ndiswrapper with a windows driver, which
again, is less than perfect. Last option is get a new pcmcia/usb
network card to replace that one.