This HSF is so good, that even at low speed it keeps the CPU cool. The Fanmate2 ensures that you have control over the speed, and keeps it at that speed. Unless you're overclocking, I'd use the Fanmate.
By the way, I just built a quiet PC with an Antec Sonata case, a SeaSonic 350W PSU, a Nexus 120mm case fan (with a Fanmate), 2x Samsung 80GB SATA drives and the Zalman 7000B AlCu. You basically don't know that it's running, even when the drives are seeking. We're talking S-I-L-E-N-T!!