Can you control the volume? If so, just turn it down and 4get about it! Otherwise, I dunno! Maybe you should talk 2 ur friends, my friend helped me when I had problems with my computer!
BigR, Where is the sound coming from? It could be a few different things, a fan going bad, your hard disk, a CD in one of your drives or maybe it is your speakers... Be a little more specific and we'll see if we can help you.
Yeah, you may have to much dust in your CPU. Is it sitting low or close to the ground? You may need to get a can of compressed air and spray the inside of your CPU.