You should just buy a fan speed controler that mounts in one of your 5.25" or 3.5" bays and hook your fans up to that. Then you can just use the same cpy cooler but turn the fan down a little and make it quiter, and that should still give you better cooling then a fanless heatsink.
Or if you dont want to use up one of your drive bays, Zalman has a fan speed controler thing called the "FanMate" and just connects to one fan and stays inside the case, and lets you have complete control over the speed. I think it would be pretty good for what your trying to do, and its only like 6 bucks on NewEgg. Heres a link: ZALMAN FanMate 2
Or if you want to spend more money Zalman makes CPU coolers that still use fans but are supposed to be pretty much silent because they use a good heatsink and the fan dosnt have to run as fast to get good cooling compared to say stock CPU coolers. Look for them on NewEgg.
Hope this helps ya.