Hello ncdave,
Welcome to the HP Forums! I hope you enjoy your stay!
I understand the computer sound drivers are not being installed. This computer does not have Windows 7 drivers. Therefore, it probably will not work. I would return the computer to Windows Vista and then try installing those drivers. You can locate these drivers here: HP Pavilion dv9720us Entertainment Notebook PC Drivers
Thanks for posting on the HP Forums! Have a great day!
Mario
