If anything, if quickset says your wireless is off, and you cant detect any networks that you know exist, then it maybe a defunct with the led.
I know in some cases when I ran the laptop either with the AC adapter or just on battery only, that when I am using the wifi, the wifi led turns off - however the bluetooth led stays on. This is only an asthetic problem in my eye so I didnt even pursue any technical assistance.
See what the dell support forums hold in terms of anyone else that has the problem. I would suggest the phone support but I went through hell and back to talk with an indian guy every time (and this is when I ordered my bluetooth module). No offense to Indian people, but their accents are thick and hard to understand - like my ears and mind cant respond to their frequencies that they broadcast clearly.
Anyways, see if that helps. Also, get driver updates for your wifi device if you can.