Dude, your post makes no sense. Are you guys talking Zalman Flower cooler or the QuietPC type fan (Molex) setup? I thought Zalman makes a standard Heatsink too? Anywho, for a standard non-overclocked Athlon XP, Thermaltake is prolly the best route. Unless you get fancy and start taking the best heatsink (aruguable) and mix and match fans with varying sound. Delta is whiny, Sunnon is as fast, but creates less pressure, and more of a Whoosh. Each fan company's fans have a distinct sound.
Personally I use a 31cfm Thermaltake 60mm fan and an Alpha Pal-6035MFC heatsink. Not silent, I can hear the fan, but it's not an ear peircing turbine that my black Label Delta was.
Basically you have to find a decent heatsink, aluminum or copper, I prefer aluminum with copper inlay, and match the fan you can stand while getting maximum CFM.
<b>"These are my thoughts, your mileage may vary."