This is one of the discomforts I have with the overclocking community at large... There shouldn't so much subjectivity over what constitutes "silent", especially when you are trying to give suggestions to people about what to buy or not buy.. It is often the case that people's sanity hangs in the balance with respect to noise generated by fans.
With the retail Pentium 4 fan at 3100+ rpm my cpu worked between 40 and 45 degrees, I changed to aeroflow to get a better cooling solution because I'm planning to overclock, but the cpu temperature with the new fan at 5400+ rpm and in the same enviorment is sometimes worst than 45 degrees.