Downclocking my desktop

My desktop computer is super loud - is there anything I can do to lower the fan noise? I'm downloading extremely important files so I can't shut it off right now, but the noise is bothering my roommates and myself .

I'm thinking something along the lines of Stealth Mode in the new Alienwares, which downclocks everything so the fans don't spin as much, leading to less noise.

Would anything like this be possible for a desktop computer?

Any help appreciated. Thanks

EDIT: What's the best program to monitor computer temps?


EDIT 2: IT WORKS!! My computer is making NO noise, my keyboard is louder than my computer!! I used these settings. Apparently I shut down all my fans with these settings, hopefully all the readings are correct...

 

one thing you could do is take the bottom off and clean the fan and cooling fins or what ever cooling devices you laptop uses. My laptop was running between 60 and 78c after four months, so i opened it up and took the fan out, then took the heatpipe and fins out.... they were cloged with dust. after using a toothbrush to clean the fins out, i reassembled the laptop and now the fan rarely kicks on and the temps average about 46c maybe 55c under heavy loads.

hope it helps,
bigozone