I had to fully rest my pocketPC and so lost my previous driver. I have spent several weeks trying to reinstall wifi. The proper driver from SanDisk does not work - it gives the 'PegasSTA.exe component not found' problem. In desparation I installed the driver for the 256 MB + wifi card and it worked!!!
http://www.sandisk.com/retail/drivers-sdwsdb-256.asp - choose the Pocket PC 2002 driver.