Problem: Like the OP above, I have made a fresh install of XP on an Optiplex 745. I did download the drivers direct from Dell, using Dell's hardware detection to match my system. I plug my speakers in - I get nothing. I pull the speakers plug, I get sound... through the internal speaker. Neither the front nor back sound ports work.
What shows up under the Hardware tab in Control Panel>Sounds? and what is set as the Default Device under the Audio tab?