The retail AthlonXPs seem to use the coolermaster DP5-6H11 or DP5-6I11A (I can't tell a difference, but one of the two), which works just fine, and aren't extremely small. In fact, they are excellent for being retail HSFs. However, you can never be too safe (unless you're like me, cooling a duron that can be replaced for $40 , so isn't worth a $20 HSF), so you may want to get a better one.