This needs some special care. You might have to contact HP to get the correct driver. I wonder if they will give it to you. They aren't enthousiastic about downgrading Vista once you bought it.
See: http://www.alexnolan.net/articles/installxpsata.htm
Hope this helps.
Kees
HI guys,
I am fed up with Vista.My laptop model is hp pavilion 6548ea that came with Vista and I want to change it back to XP SP2.Help me please.My SATA hard disks(Seagate) weren't recognized when i installed using the Xp boot cd.
I have gone thru all the "Downgrrading to Xp" forums, But couldn't get my resolved.

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