if you bought a cheap case with a power supply included, you have a really cheap psu, they make noise, if you buy a good one, they are usually very quiet. as for the cpu, either buy a really good fan, i dont like to post names on most things(sparks a ford/chevy debate) but i use a coolermaster, very quiet, and my athlon 2800+ is happy. to get even more quietness you would have to water cool, almost no noise. if your case is a really cheap feels like a beer can, it to will cause noise.