They do not use standard Windows drivers. There are special drivers for them.
You probably know this, but PocketPC is NOT technically a Windows OS. It looks a lot like it, but the underpinnings are totally different, basically because of the hardware archictecure.
Nice thing is, if you find one driver for a device, it will probably work for other brands. For example, Compaq puts a driver on the disk for their WLAN card, the 110. This driver also works for the DLink WLAN cards because they both use the same chipset.