The School has purchased 16 Dell Optiplex 380 PCs and all of them have come with Windows 7 Pro preinstalled. I would like to install Windows XP Pro as part of the downgrade program. I already have a Windows XP Pro OEM CD Media, but how do I get the product for Windows XP Pro? Do I need to contact Dell or Microsoft? Also no Windows XP Pro downgrade disc was provided by Dell.