In that case DONT try and pelt coold your CPU!!!!
From what I have heard around the forums here, the maximum pelt you can cool with a Heatsink + Fan combo is an 80W pelt and that pelt is TOO small for an Athlon or an XP. The Xp will put out around 65-75W of heat and an 80W pelt will just cause it to fry.
Unless you have one giant heatsink + fan combo.........like the size of your case