Is there any chance the speakers are too antiquated to be used? They seem quality...a left and right with a subwoofer.
On my old gateway (purchased in '99), there was a trick to getting the audio to work. I was running XP, I had to click on the master volume window (containing all the difference volume levels), options, properties, advanced, and either click or unclick a radio button saying something like "digital output" or something. Strange that radio button is not on this new computer with XP but that must be because of the HD audio on this system.