Dell's ATX style cases are made by Palo Alto, who also made some Micron PC and HP business class workstation cases. They are all the same except for minor cosmetic differences to the plastic shell. You can do a search for Palo Alto and find venders.
<font color=blue>Watts mean squat if you don't have quality!</font color=blue>
Crash makes a good suggestion... Dells are usually very quiet.
But there may also be some things you can do to quiet down your existing case...
1) Get that heavy rough surfaced self-stick vinyl they use on bathroom windows (most hardware stores have it) and line the sides, top and bottom of your case with it. Be careful not to block cooling vents...
2) Put 10 ohm 5 watt resistors (widely available in electronics stores) in series with the power leads of your fans. This only knocks about 5 to 10% off the speed of the fan and has a minimal effect on cooling, but it does quiet them down rather noticeably.
3) Shock mount your Disk drives. I line the disk bays with two layers of vinyl electrical tape before installing dives. This minimizes vibration of metal against metal and can sometimes quiet a drive down a fair bit.
4) Shock mount your fans. Cut small washers made out of bicycle inner tubes (or similar rubber) and put them between the fan and the case and between the head of the bolt and the case. Again, this minimizes vibrations being transmitted through the case.
4) Increase air intakes... not by adding fans, but by enlargening the air intake openings at the front and bottom of your case. Fans run quietest when they aren't creating a vaccuum.
5) Cut down on the number of fans. With good airflow you should only need one fan in the power supply and one case fan for adequate ventilation on an average system.
6) Cover unused exhaust fan openings. I make flat squares, the size of fans out of plastic and bolt them in through the pre-drilled holes. If you have good air intake at the front, this can actually lower case temperatures and it blocks sound from travelling out the open holes.
7) Place air deflectors on the output vents (where your fans are), a simple home-made cardboard cube with the back and bottom cut out, taped over the fan openings should suffice. This deflects sound downward and away from the rest of the room.
Thanks to both of you for taking the time for some really useful advice. I had started to take measures in quieting my case by suspending my Maxtor hard drives with elastics. That helped a fair bit but its my CPU fan that's loud. I'm going to try Teq's suggestions first 'cause it's the cheap solution.
He was talking about an old trick from the 386 days when drive heads used to sound like popcorn going off... Loop a long elastic band through the drive bay and hook the ends over the hard drive so it was suspended in air underneath. Worked too... until you forgot about it and picked up the computer that is.
I've found that 2 or 3 layers of black vinyl electrical tape on the bottom of the bottom drive bay, with the hard disk bolted in from underneath is usually all it takes to quiet the new ones down. To get real exotic also put a washer and then a rubber washer on the bolts... works even better.
I have an Athlon 1700 XP+ with a Thermaltake Volcano 6cu+ fan. I'm currently not using thermal paste with it. It runs at about 43C in a fully enclosed case with no other venting other than the PSU. I have insulated the case using sound absorbing ceiling tile. It cuts my perception of how loud the CPU fan is in half. The Thermaltake 6cu+ operates at 39db. So how many db I shaved off is 10db? (I'm just guessing)