No. Its not my speaker i checked it with other system already. The same thing happened to my old system which was quite similar to this system i had 512mb of ram and ASUS P5B-MX motherboard. It was working one day and the next day it stopped working one side and after a few days both the sides stopped working.
So i install a new sound driver but didnt work. So i just tried installing an update of the chipset driver and it started working again but only one side.
So the next day i decided to buy a new system which consist of the above description but still no sound. I even checked the powersupply, no luck on that. So i reduce my problem to only 3 things now(some may not sound relevant) my old IDE HDD, my dvd and my new borad is bad.
But before i claim it i would llike to hear some professional opinion.
I did a clean install of windows XP SP3 so i dont think there is a driver conflict.