well, XP's and MP's and mobile XP's were all the same core and packaging (socket 462)...to set thier mode all one had to do was modify the state of some of the bridges on the top of the chip package. this is what i did. i bought a pair of XP's, painted over the bridge to activate MP mode, popped them in, and away i went!
one could also do this with some of the durons, and older tbirds of socket 462 factor. it is a very easy and cheap way to have a powerful dual system