Well, as per as Web site goes, ur system uses,
Analog Devices ADI 198x Integrated Audio u may try downloading the WinXP x64 drivers and try it with Vista x64 !!! *support.dell.com/support/downloads...=3&impid=-1&formatcnt=1&libid=3&fileid=125744
anyway, i am not sure whether ur system has a HD audio or not, as here u may find driver for same divce but HD drivers
*support.us.dell.com/support/downlo...eid=R140162&formatcnt=1&libid=0&fileid=187309