The cheapest way is to remote mount your computer in another room with KVM extender cables. Is this an option for you?

If not, try to identify the main offenders in your system and replace them. A great quiet PS can be had for $60-$70. Nexus is my favorite brand; I use their NX-3500. Zalman, Antec, and Enermax all have nice offering as well. CPU fans will set you back about $30. A nice case fan like the 120mm fan from Nexus can be had for about $15. If you need a new case, try an Antec Sonata - probably the best 'quiet' case for the money. FWIW, I use a Nexus Breeze case. As for hard drive enclosures, ask someone else, becuase I have no experience with them. I've never had a need; I use Seagate Barracuda drives suspended by rubber in Zalman heatpipes, and i've never heard a peep out of them.

One more idea... you can modify the speed of your fans with fanspeed controllers, or if you're on a real budget, resistors. However, If you do this, monitor your temps carefully.

putting the computers in a different room is not a viable option. My cables will not reach that far. It sounds to me that the fan is the biggest peoblem. It doesn't sound like the case is a problem.

I don't know about the HD. It seems quiet, but I can't really tell where the majority of the noise is coming from

buy a bucnh of quality fans, an dput them at 5v. raplace the cpu cooling with Zalman 7000/7700, the northbridge fan with the zalman northbridge heatsink and try to find either a graphicscard without a fan or a passive heatsink for the graphics card you have now. Replace your PSU with a Zalman PSU or a OCz PSU. If you can still hear your computer, your hard disks are the porblem.. Samsung and Seagate both make very quiet hard drives (the samsung's are quietter IMO).

Quiet

I think David sets it apart real well. If there is a way for you to determine the loudest parts you could just begin with those, like a better PSU first, then a better CPU-fan/cooler. With each step you determine if it is quiet enough for you as opposed to buy it all in one go.

I believe the Antec Sonata case is sold including a (good) PSU, so weigh that in if there's is a possibility you will go that direction.

From what I have read on topics of silencing your PC, it is best to attack noise at the source rather than trying to smother it with dampening pads that will arguably increase the case temperature.

putting the computers in a different room is not a viable option. My cables will not reach that far.

But that's what KVM extender cables are for! KVM=keyboard video mouse. Are there other cables running to your computer? USB and FireWire can be extended, too. Do you have proprietary cables with your soundcard or something? If so, talk to the OEM and find out if they have logner cables available.

I like my silence case. I know its $500 but it was money wll spent...

For the record, 80mm fans are the devil. Arctic Cooler has some seriously quiet ones, but most stock and aftermarket 80mm's are noisy as hell. 120mm's tend to be quieter. If your case has room and otherwise adequate ventilation, some Auralex SheetBlok can be put inside to help quiet it. I believe this is what a lot of the "Audio PC" manufacturer's do. If you have good enough ventilation throughout the rest of the case look into passive CPU coolers. Thermaltake makes some nice ones, but the good ones are pretty big, so make sure you have room.

quiet psu fans are a hellava lot quiet than some really crappy noisy ones. I've got a Nexus one in my old PC, it made so much difference. Felt like a tenth of the noise. And pretty cheap. Maybe try that first, it might be all you need to chill that jarring sensation. After installing it my hard drive clicking away when when recording in the same room as the comp was more of a prob than the fan noise... but they were cheap ones that click more. Far from ideal recording, but was fun at the time. An alternative half arsed sollution: cupboard?

jah bless

How about liquid cooling? It'll run you about 200, but it's pretty damned quiet.

yeah the main noise is coming from the psu fan. I can really tell now once i really inspected it.

Doesn't seem like the cpu fan is loud at all.

The only noise that i can tell now is the noise from the psu.

I saw some info about a fanless psu. But I don't think that would be a great option. I don't want to overheat.

Any more suggestions on really quiet psu's?

Antec makes quality PSU's, some models are quieter than others though.

right but how quiet do i need it. The fanless are 0dba. Most of the other ones are between 10-12---16---25 dba

The quieter your computer, to more dynamic range you can get out of your speakers without cranking them up. When I first silenced my machine, I was pretty amazed at how low I could keep the levels and still have clarity. That said, I wouldn't buy a fanless PS. The Nexus is very close to inaudible about a meter away from my computer.

If money were no object...

Antec Phantom power supply...passively cooled.
Zalman quiet cooler, all copper.
Good quiet case, like the Antec P180.
120mm fans, all linked to a fan controller.

You'll still have hard drive and optical drive noise though.
I don't like putting quieting sleeves on hard drives, because it can shorten their lifespan.

This is what I am running:

http://www.antec.com/us/productDetails.php?ProdID=24350

http://www.antec.com/us/productDetails.php?ProdID=75013 (times 3)

http://www.coolermaster.com/index.php?LT=english&Language_s=2&url_place=product&p_serial=RL-HUC-E8U1/E8U2&other_title=+RL-HUC-E8U1%2FE8U2+AQUAGATE

http://www.antec.com/us/productDetails.php?ProdID=77042 (to replace the noisey fan on the Aquagate)

My comp is extremely quiet now (my LDC can't hear it from 8' away) and rarely sees temps over 120F with an overclocked P4 2.8Ghz.

I was going to go the acoustic case or cabinet route but was really worried about the lack of ventilation and overheating. Just remember to keep an eye on not cooking your computer in an oven while trying to shut it the hell up.