http://h20015.www2.hp.com/en/taskPageSelect.jhtml?reg=&plc=&lc=en&cc=us&prodId=hppavillio28316&pagetype=software&docparent=software

HP writes " There is no software available ..."

Since Microsoft doesn't supply drivers for machines, to fix this one I would:

1. Disable the onboard sound (BIOS, Jumper, read the manual, look in the BIOS.)
2. Decide if I will use a 10 dollar PCI sound card or some Turtle Beach or Creative Labs PCI sound.
3. Install new sound card and drivers.

In closing, your "professional" installer seems to be not so professional to not have resolved this with you. It's 10 dollars to fix. How much was that install and did they:

a. Supply with the 2000 CD.
b. Supply a CD with the SP4 and what else they updated the OS with.
c. Install a firewall or at least the MS Blaster fix.

In closing, do not put any CD in the unit that came with the machine unless you want to go back to the installed OS.
Bob