If the Service Tag label is legible on the case, go to your local Dell website and input that in the Support section. That will lead you to the drivers for all the specific equipment that went into your machine.
Or look in Control Panel>Device Manager and right click the wireless adapter then choose Properties. Under the Details tab nore the VEN and DEV references and input them in the boxes at www.pcidatabase.com. That will lead you to the right driver.