Hi guanacoperdido,
You may download the wireless driver for your specific system from the link : http://dell.to/QjjZDA
Enter the Service Tag of your system -> Select the Operating system installed on your computer -> Expand the Network tab -> Download and Install the wireless card driver for your system and restart the computer.
Before installing the driver, ensure that the wireless is turned on. You may use the Fn+F2 button on keyboard to toggle wireless on/off.
Please reply if you have any further questions.