It sounds like you haven't installed the sound/audio drivers, which aren't part of XP and which you should be able to get from the Dell website. There may be other drivers you need to install too - look in Device Manager for yellow exclamation marks.
If you get really stuck, download the free version of Slimdrivers. It should see the missing audio driver and allow you to download the correct one. Ignore any other driver updates it recommends (if it aint broke, don't fix it!).
I have run and installed ALL missing drivers from SlimDrivers, but still no different. Control Panel > Sounds & Audio Devices, the Volume & Audio tabs are totally greyed out: Volume tabs saying "No Audio Device."
Any more ideas?
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