Maybe you have to go into the BIOS and look for an option to turn the onboard sound "on"...it could be turned off in the BIOS.
If its a dell it probably has a label or tag on the back of it called a "service tag" with a number on it. You can go to Dells site and enter that number and it will show you all the specs etc and probably have drivers also.
Here is the Dell page for Dimension L series comps
http://docs.us.dell.com/docs/systems/dmum/
and igf you click on "technical specifications" and scroll down you see that if seems to have this audio
http://docs.us.dell.com/docs/systems...pecs.htm#audio
Creative Sound Blaster Audio PCI chip with 64-voice wavetable synthesis
So that would be the driver you need
As a matter of fact I think with Dell that you can go to their site on HER Dell computer and it will search her comp and tell you all the specs etc...and probably you could get drivers that way.
If you go here
https://support.dell.com/register.aspx you can eneter your service tag number....or you can click on "find my service tag" and it will go to the utility that searches the comp etc.
That oughtta get you going, JP