Core speed of the AthlonXP 1500+ is 1.33GHz. In today's market, we have AthlonXP's using both the Palomino core and the Thoroughbred core. Palomino and Thoroughbred have identical functionality and performance, but the Thoroughbreds are made using a smaller 0.13-micron lithography, and use a lower voltage, so some boards support both flavors of AthlonXP's and some boards only support Palomino variants.
You can tell the cores apart by several means, one of which is appearance:
How to spot a Thoroughbred Note the rectangular core and the black label stuck to the edge of the CPU on the Tbred.
I can't get through to Asus' CPU Support page right now, possibly they have their server down for patching against that SQL worm or something. It would ordinarily be
here. This thread may help you in the meantime, however:
click me