My friends Compaq Presario C770TU laptop started having issues with external headphones and microphone being not recognized by Windows XP, contacting HP support regarding the problem resulted in the response below with links to download Windows XP drivers :

"I would like to share that the above mentioned notebook has not been certified on XP and hence not supported. Hence we would not encourage the use of NON-Certified drivers on the product as it may lead to degraded performance and damage the product in some instances which would then not be covered under standard warranty.

However if you would like to pursue Win XP installation on the product, I have captured the links below wherein the nearest compatible drivers are available."

First of all its very bad on HP's part to not support one of the world's most successful and widely used operating system, secondly the audio driver they sent links to download does not solved the problem, I had to try different Conexant audio drivers to finally find a working one , if you are having similar issues with your HP laptops follow the instructions ahead to get your headsets working on Windows XP.