Hi,

i'm using a D-Link USB 2.0 Cardbus Card and an Edimax WLAN Nano Stick with my Pismo (OS X 10.4) with WPA2 etc. (bought them from Ama***):
http://www.edimax.com/edimax/merchandise/merchandise_detail/data/edimax/global/wireless_adapters_n150/ew-7811un
http://www.dlink.com/-/media/Consumer_Products/DUB/DUB%20C2/Datasheet/DUB_C2_Datasheet_EN_UK.pdf
 
Driver Edimax  (OS X 10.4):
http://www.edimax.ru/images/Image/Driver_Utility/Wireless/NIC/EW-7811Un/7811Un_MacOS10.4.X_Driver_1003_UI_1.7.9.zip
 
For OS X 10.3 and 10.4 no driver is needed for the D-Link USB 2.0 card.