I can't give you a concrete answer, since I've never seen that fan before, but yeah, it should be around 19 dB, since 21 cfm isnt alot of air.
enermax makes a great 80mm quiet fan. check newegg. i believe it's like 18db or around there. i picked up 2 from the egg and they are perfect. one is my intake fan and other is on my cpu (amd 64 3000+) heatsink. very quiet and temps still low.
is this the fan you were talking about? I think I might get that one now, only 6$ more total, and it says it's quieter and moves a little more air.
yes, that is the fan. like i said before, it's really quiet and keeping my pc cool.