I've seen the SilentPC site but their reviews i find are few and far in between.
They have some great tips on silencing issues though that i've used on my system.
Next two major changes towards silence include adding a water cooled system but using a quiet, slower pump not really for high end overclocking (e.g. the
Zalman Reserator).
Second, moving to SSD for storage.
The two loudest components in my system are:
CPU fan (just using stock for now)
HD data seeking and platter spin
Otherwise my comp is almost dead quiet.