I don't know how accurate this is, but in my experience with green Athlon XP 2000+'s, they're Palamino Core CPUs. Really there isn't much difference between palamino and thoroughbred, except that the palamino is a thoroughbred that's designed for multiprocessor use. Same 256kL2, 266FSB... However, I've also seen some Palaminos that are burgundy in color, the difference is the micron process.
P.S. - After writing all this, I'm realizing that harrack52 already said it better and said it first; so "what he said" ;)