I recently ordered the swifty mentioned above. I'd like to top it with a near-silent fan. Would it make sense to add an adaptor to use something larger than 80mm?

I'm in the middle of overhauling my rig:

Stock Enlight 7237
Noisy 80mm front fan
Enermax Whisper 465
AMD 1700+
ThermalTake Volcano 5 HSF
ECS K7S5A
ATI Radeon VE Dual Head OEM
Aardvark DirectPro 24/96 6 channel Soundcard
256MB DDR
Various HDDs in cheapo Future Power Mobile Racks

I plan to:
Replace the stock front fan
Add another input fan in the bottom of the case
Add a blowhole (80-120?) in the top center
Replace the TT Volcano with the MCX-462U (and some fan...)

And some other stuff...

Queue

i have the swiftech and replaced my delta with a 92mm low-RPM papst using the amuzuma fan adapter (open non-funnel adapter) running on 12V. it's fairly quiet, but can be slightly heard over my other case/PS fans (no fan on chipset or gf2 vid card) since they are running undervolted. depending on your noise tolerance level, this may or may not be quiet enough for you. i also tried placing an 80mm panaflo L1A. it ran about 5-6 degree C higher than the 92mm setup i described above for me. i also tried using the zalman fan bracket to mount a 120mm L1A panaflo. the 92mm/adapter setup and the 80mm setup was much cooler than this setup. my temps on a athlon XP 1800+ run about 15-18 degree C over ambient at full load (measure by socket island diode so may not be accurate!)

personally, the MXC is not the cheapest or most optimal setup for low-noise as the swiftech does not operate at optimal performance until some decent LFM is running through the pins. still, my temps are low enough, and even though it's fairly quiet, i would prefer a setup that is nearly silent (instead of fairly quiet).