Hope this saves someone the frustration I went through. This is the top solution that worked on a Dell Inspiron 15 (3521) with fresh Windows 7 SP1.
Windows 7 does not include native support for the Qualcomm 9565 chipset found in many Dell laptops (like the Inspiron and Vostro series). You might see the WiFi light on, but no networks appear. Hope this saves someone the frustration I went through