no audio output device is installed

If you need to install the audio drivers for your model, you can review the Dell's product support page for the 1501.

Choose Drivers & downloads

By default Windows XP is selected as the Operating System(OS). Click Change Operating System if you are using Windows Vista.

Once, you've selected the OS, choose Audio. The Sigmatel files appear to be the default driver for XP and Vista, however there is a Creative Labs driver for Vista as well.

Choose Download File

Save the File

Once the file has completed, double-click on the file to open.

The setup for installing the drivers should appear on the screen and direct you on completing the installation

I recommend rebooting your computer, ensuring that your volume is set to high and test an audio or video file if you have one saved on your computer or view a video on Youtube to verify the sound is working properly.