To save some reading, I think this sums it up best (from Anandtech Barton 3000+ review):
"The areas in which the Athlon XP does quite well, including the new Barton core, are its conventional strong points; in business applications it dominates the Pentium 4, showing off a very conservative model rating, in games the chip is quite competitive with Intel but once we shift to the newer multimedia, encoding and rendering environments the Athlon XP is no longer able to do so well. "
So in games to XP core is a little ahead like one of the links in the above posts shows. (as of todays games)