having some system specs would be helpful, so that we can have a general idea of how hot your computer is running and what components are generating the heat.

Your first line of work should be figuring out what produces the most noise. Having a bunch of slow moving fans isn't going to really make that much of a difference. However, I noticed several of those fans that are ridiculously loud. Firstly, your HSF fan looks like a 60x60 7000rpm fan. I think i have the same one, or something similar. It gives out a very loud whine. Get rid of it. If your HSF needs a fast moving fan to make it effective, get a new HSF (PM me, i've got several good ones lying around that i could get rid of . . i don't know about extra fans though).

2) your vid card fan is LOUD (right?) This is hard to fix as it is a stock cooler and the card needs that much air to keep it operating safely. THere's not much to do about this except getting a card that doesn't need a liquid nitro supply to keep it sufficiently cool.

I would go ahead and get rid of the drive coolers and attempt to put an 80-92 mm (doesn't need to be more than 3200rpm or so) fan in your HD bay as another intake fan and put your HD"s there. I've found this setup cools better than those custom coolers and is probably quieter (since a larger fan can move slower while cooling as well).

I've not used that PS before, but are any of the fans particularly loud?? I mean, it's only a 450W PS. I've seen 600+W w/ just two fans, go ahead and disconnect one (but not the exhaust one).

Do those 120fans make a lot of noise. They are probably most exposed to air and therefore more able to make noise. Thus i'd see how your system does with one or both of those unplugged. Also, those side fans, unless you have a hopeless case, can really interrupt airflow. Try to arrange your cables and fan such that you have a decent amount of pressure coming into the bottom front of the case (to cool your HD's) and exiting the upper rear of the case (to pull air over the PCI cards and then get rid of the hot air from your cpu/hsf.