can you not just back up your data and do a fresh install of XP and tehn 7? surely this would be the quickest way....
From the infor you have given the driver it is asking for is the 82801 SATA RAID Controller. So you probably have Sata set as RAID or AHCI? So in teh ory the driver you will need with be the XP Intel driver matrix storage manager Os pre installation only from teh dell website, and i would hazard a guess that it would be for teh Optiplex that you would need it.