Try listening to 2 CAK38's, PSU fan, 2 rear fans, 2 front fans, 2 HD cooler's w/fans. And that's just in one system. The other has one of those monster 3-fan Pentium III heatsinks (don't remember the brand) with 2 rear fans, PSU fans (2), 1 front fan.
And then there is my fish tank with it's pump. hehe