CPU fans aren't usually the cause of loud noises, good aftermarket heatsinks/fans are usually big enough so they don't need to spin as fast to preduce efficient cooling, noises from fans on the case/PWM/Chipsets are far more noticeable. If you are really picky about noise I'd suggest going with water cooling system.
Depends what you want the CPU for...
For a word-processing/net browsing machine I'd go with a low-power AMD. TDP of 45W and will run nice and quiet with so such little (relatively) heat dissipation to do.
For a high-power machine i'd probably go with a an E8400.
CPU temp and thus fan speed can be change dramatically with a decent case and decent airflow though.
My 6000+ which as I'm sure you know is a hot-running CPU (125W) idles at between 28-31C in my case (CM 690) on the stock cooler!
Fans become loud when theres dust in them. Maybe you could try cleaning it up...vaccum it. .
NOOOOOooooooo! Vacuums can create lots of static from the friction of air moving in the hose. Think lightning. The best way to remove dust is with compressed air. Take it outside on a nice day and give it a blow job.
The swiftech compact water cooling setup is excellent for cooling, simplicity and price - the noise isn't actually much quieter, your just changing the pitch. Moving the box away from your head as far as you can would make things quiet. under a desk, behind a panel or something along those lines makes for a more effective solution as well. Zalman fan controllers on all loud fans will slow them down effectively. Power supplies with variable fans get noisy as they get hot, getting a more efficient bigger fan on the thing helps, having 2 quiet 80mm and 1 quiet 120mm blowing through the power supply will result in a cooler and much quieter solution, and as a bonus you get to void your warranty.
Keeping a system cool has to do with alot of things and the first place to start is the case.
I perfer the older CoolerMaster Stacker TO-1 as it is -still- the coolest running case for air cooled system.
I also has lots of room if you want H2O pumps or an oversized dual CPU server MB.
The air intake fan,CPU area and exit fan are all in a dirrect path giveing the best airflow pattern...and the intake is also the the HD cage that can be moved to any position on the front which has 11 bays.
Add the optinal Crossflow fan which pulls air in from the MB side of the case and moves 34 qfpm over the MB from top-to-bottom cooling all the chips,voltage regulators and RAM at the same time.
The rear exit fan grill can be removed via screws futher boosting the airflow well over 80%.
---> This should be done with -any- case you have even if you need to cut it out of the way!
Using a Thermalright HS gives the best air cooling of any brand...dirrect it's flow into the exit fan.
The systems in my profile runs 2-3C over room air while running benchmarks (100% CPU load) and they are all OC'd 50%.
EDIT: I built another system about 2 months ago with a dual core 6000+ and a cheaper Zerotherm Nirvana and it runs 6C over room air temp.
The key is corrct airflow which only needs -one- intake and exit fan...more fans on the side disrupts the flow pattern.
Removeing the exit fan grill on an old case that had a 3200+ Barton dropped the CPU temp 25F alone...thus I have done this with every build I make for myself and others from that day forwards.
By the way...
You do not want to feel hot air comming out of your PSU...it is not a exit fan and hot intake air makes it work harder,lowers the OC your system can reach and shortens it's life span (and everything it is connected to when it dies).