Battlefield 3 is not compatible with Windows XP.
Battlefield 3 was engineered to revolutionize gaming with superior processing, animation, physics, sound and visuals. Older operating systems (2001 and earlier, such as Windows XP) cannot support the advanced computing power of Battlefield's Frostbite 2 engine. To realize the full potential of the technology, Windows PC players will need to run the game on an HD system supported by Windows Vista or newer.
I am sorry but there is no official workaround to run the game on Windows XP.
Cheers
Basti
