If you aren't going to overclock, you can always set your motherboard BIOS (if supported) to run the CPU fan in silent mode. From the looks of the fan, I'd say noise level is the same as stock dual core.
If you're gonna spend for the 9550, it's worth another $30 for a quiet CPU cooler. I between mu Zalman. Rosewill. and Artic Pro CPu coolers I use, I find that the Artic Pro Freezer 7 to be the quietest and the only one with rubber grommets absorbing and reducing fan vibration and noise.