@ auszombie
Your current PSU should be enough for the hardware you are running, replacing it for another one will not lower the temperature much as most is generated by the hd's & cpu
What you can do is just replacing the fan itself for one which runs more silent this would be the cheapest option
You could also add a resistor to the fan lead, instead of a fan controller, to make it run slower BUT this will increase the temperature of your PC.
If I build a PC I always have at least 3 fans in it (excluding vga fans), one in the PSU (default), one in the front of the PC, to get air into the PC and one at the back to get the air out again. Usually I add resistors to slow them down enough to get enough air in and get them to run silent (as much as possible)
Don't underestimate harddrive cooling as this is the nr 1 cause of dead for them! Have a look here to "solve" this problem:
http://www.coolermaster.com/index.ph...ist&p_class=99