If they don't help you overclock, they'll help by keeping everything cooler. I ran my computer for a year in a puny Micro-AT case with no fans, and it ran fine. When I got a new full-tower ATX case I put in an intake fan blowing on my hard drives and an exhaust fan sucking from the CD drives. My stability and overclocking haven't improved any, but there's a lot of hot air coming out by the CD drives. Along with the PS blowing out, everything in there is a lot cooler and should last me a while more.
"If it's not on fire, it's a software problem."