its sooooooooooo loud!!!  and i do not understand why.  my sister just got a new HP Pavilion Desktop, and it is completely silent!  Under full load, you can hear her fan speeding up, but still it its very very silent.  Here is what's in my computer:

http://www.thermaltake.com/products/chipset/tgf020.htm">TT Blue Orb
http://2cooltek.safeshopper.com/26/40.htm?851">2x Sunon 80mm fans
Stock AMD heatsink
Stock PSU fan (VPower)

Which fans should I replace?  When I bought them, they were rated as fairly quiet, but they are not quiet at all.

This is just a TT Blue Orb - It is a chipset cooler which I have installed on my GFX card. 

I think everything I have sucks, and is loud.

Im taking any/all recomendations on 80mm case fans, and cpu heatsinks.  My temps are higher than I'd want, and the sound is unbearable.  So please, recommend what you have if it is quiet.

OK thanks Elliot.  So you use 4 of them and it is very quiet? Nice.

I just did some fiddling with the fans in my comp.

With just the AMD Heatsink and PSU fans, my comp is still considerably noisy...not that loud...but still not as silent as my sisters HP.

With the HSF, PSU, and TT Blue orb, it is about the same sound as w/o the TT, but i notice a different frequency in whirring.

With the HSF, PSU, TT Blue Orb, and both Sunon fans, I reach Boeing 747. 

So i have decided that the Sunon case fans must go.  The HSF wouldnt be a bad thing to replace either...  So still, any more recommendations would be great.