If you do not have the original HP drivers CD then I would not recommend you to format your harddrive... because after you reinstall your XP.. you need to get the right drivers for your sound/graphics/WIFI etc.. so if you do not have this on you then do not downgrade... jus wait and hope that Vista Service Packs are out soon.. I hear that by the end of september the first service pack will be available...

rgds,

j.j