My temps don't count,as I use Thermalrights SK6 and a Delta 30 cfm fan,coupled with V-cool.
CPU temp is 30.4c normal load
heavy load is in the 38c range.
The cooling difference between the 2 heatsinks you've chosen is nominal.
The one I'd choose is the AX7 coupled with a variable fan.
The advantages are the aluminium fins allow for quicker heat dissappation(sp?) and is 1/2 the price!
Currently running a Duron 800@1000mhz.
See here:
http://heatsinkfactory.com/cgi-bin/H...ight%20Coolers