It's been awhile since I installed my drivers, but I think this ZIP file is just a copy off the Sharp CD-ROM.
Unzip it with the directories intact, then run the wizard or add new driver in windows.
If you plug in your zaurus first, the wizard should pop up and ask to add new hardware/drivers
When it asks for a file, point the wizard to USBdrivers\network\slz3ndis.inf