I have started using the Vantec AeroFlow on both my AMD and P-4 systems. It is relatively light, fairly quiet, and cools as good or better than all but the biggest, heaviest, and loudest all copper coolers.
Right now I am in a room with the ambient temp a little over 80 degrees farenheit. My 2.66c P-4 is clocket to about 3.3 and the fsb is a little over 1,000. The CPU temp is 39 Celsius.
My XP2400 and XP2500 Barton run about the same or maybe a couple of degrees higher even when overslocked.
I bought the AeroFlows at Fry's for $30 with the TMD fan. I liked the TMD fans so much I bought 4 more ($8 each) and replaced the case fans on two of the systems. I think Newegg has them for a little less.