Spinky,
First off, apologies for the forum member(s) who don't understand watercooling for silence. Engineering is very much a matter of making tradeoffs and IMHO they're making the mistake of thinking that their own particular priorities apply to your situation as well.
There
are some
very knowledgeable folks here - I think they're mostly tied up in another
thread right now

.
I don't claim to be one of those knowledgeable folks, but I
have been building watercooled-for-silence systems for three or four years now (one's in a professional recording studio).
I haven't used a reserator (too expensive for what it is) but if you decide to "improve" it, remember that:
- the pump is submerged in the reservoir; an inline-only pump will not work (you've probably got some size constraints in there too).
- the system is designed to low water flow; if you're looking for a better block, look at the ones that are designed for this. I'd particularly suggest the Innovatek Rev3 block
If you still want fanless, but not the Reserator, have a look at the Innovatek passive radiators (
big honking radiators with widely spaced fins). If you want effectively-silent (quieter than ambient noise level wherever the PC will be installed) then you
probably can use a radiator and fan combo (depends on ambient noise) but you want a radiator with low air resistance, which means (probably) one of the BlackIce
non-Xtreme radiators (either the 1x120mm fan "Pro" or the 2x120mm II - but
not the thicker II Xtreme). Innovatek has some low-air-resistance radiators as well. (if you're state-side, check out Innovatek gear at
High Speed PC. If you're in Europe, you have lots of low-noise choices.)
I've had best luck with Panaflo L1A fans at 5V (many fans will not start at 5V - these do fine). They are unhappy below about 7V if you use PWM, so use a resistor/rheostat or just put 'em on the 5V bus.
If you possibly can, setup your system so room air comes through the radiator - you will pay a temperature penalty if you use case air (particularly in a low-air-flow system).
Essentially there's a balance: Your radiator becomes more efficient as the temp difference between it and room air becomes greater - so your coolant temp will increase until the radiator becomes sufficiently efficient to shed the heat you're putting in.
...So your coolant will be warmer than what folks here are used to - and additional heat is your enemy. This means using as small a pump as you possibly can (Eheim 1046 or Innovatek/Eheim HPPS) and reducing water path resistance as best as you can. If you're just setting up this system, consider using one of the processors that generates less heat (my current favorite is the Athalon XP-Mobile 2400) - and use a motherboard that lets you undervolt/underclock.
There's also a whole raft of things you need to do to make the rest of your system quiet - why not go have a look at
The Silent PC Review.
Remember that there's not much point spending money to make your cooling system
lots quieter than the rest of your system.
Hoping this helps...
Bob
PS: To take a contrarian approach, if you're running windows, you could run terminal server on a not-necessarily-quiet system somewhere where the noise won't bother you and use a
terminal. If you're running unix/linux you already know about terminals.