If you ever plan on using a peltier, then get the Alpha PAL6035. If you know you never want to get a peltier, then go with the PEP66. The PEP66 was made for P3 FC-PGA's and has 4 little rubber feet on the bottom for better fitting. The PAL6035 was made for Celeron cpu's which have a much larger cpu slug. The bottom of that heatsink has no feet, and is perfect for peltiers that need a flat surface.
And just a suggestion, I've gone through many motherboards, including the Asus CUV4X, CUSL2, CUSL2-C, and CUBX. I highly recommend the CUBX. I first had the CUV4X, and the via chipset just plain sucks, chipset drivers are always a pain in the ***, and the memory benchmarks are just horrible. I could only get my 700 up to 945 stable. CUSL2 and CUSL2-C have slightly better memory benchmarks, but i could not get any game stable at ANY cpu speed. It would always crash after 20 or 30 minutes. CUBX is flawless. I overclocked to 140 fsb (980mhz) completely stable, NEVER CRASHED ONCE. I did 150 fsb (1050mhz) but Prime95 would shutdown with a program error, still, it never crashed, but i went back to 980mhz. the memory benchmarks are extremely high, in the 500's compared to the 300's of the CUV4X and 400's of the CUSL2. Also, the frame rate with the CUBX is the best. The only downside is that it does not support AGP 4X, which is not really a downside, since benchmarks have proven that AGP4X makes NO difference compared to 2X, especially in Windows 2000. The onboard sound of the CUV4X just sucks, and its memory and framerate benchmarks suck. If you have not purchased it already, please look into the CUBX.