Less noise is good.
There are multiple ways in which you can cut down on noise that a typical PC emits, some are more effective than others, and usually more costly as well. This doucument shows how to cut down on noise cost-effectively. Obviously, you can't expect miracles, but the results come cheap, fast and relatively painlessly. I tried to replace fans with expensive Papst fans with RPM lowered to minimum that kept the temperature under control, but was not able to make the darn thing any quieter. I finally settled on the original fans, cooler fan is running on 9 volts while the power supply fan still has the original thermistor - I just moved it from a power supply heatsink to power supply case.