I have Dell Optiplex 745 with Windows 7 installed on it. I'm trying to use the Windows XP audio driver as Windows 7 drivers aren't available for Optiplex 745 and Windows Vista driver is displaying that it's not compatible with my hardware. When I try to install the Windows XP audio driver, it's displaying an error HDA audio bus driver is required and not found The installation fails then. I have researched thourghly and used many drivers but my audio is not working at all. I was also told that it might be a problem with my hardware – that is, a problem with the board.