In the order you mention things (kinda):
GB GA-X48-DS5 w/f8a BIOS - Q9550 stepE0 @ 3.825Ghz:
Arctic Cooling Freezer7Pro w/92mm PWM 'daisy-chained' to CoolIt Systems RamFan w/EverFlow F126025BU 60mm PWM;
Sunon KDE1204PFV2 40mm/NorthBridge; EverCool EC3010M12CA 30mm/SouthBridge;
8Gb (4x2) 1066 G.Skill F2-8500CL5D @ 1080 (DDR2-8640) 5-5-5-15 on 2.4(6:5)mult/1333strap...
CoolerMaster Cosmos 1000 w/Silverstone SST-CMD01 ESA 5ch fan controller/4ch temp sensor:
3 Arctic AC12L exhaust (top x 2 + rear); 2 Scythe SF12D (HDD cage top + rear); Scythe SF12E bottom intake...
Koutech IO-FPM220 3.5" Floppy & Card Reader; 2 IDE DVD's;
4 150Gb WD Velociraptors in two RAID0 pair-OSs & swaps; 2 1Tb WD RE3s in RAID1-data; 1 Sg 1.5Tb backups...
Multiboot via BootIt NextGeneration:
VistaUltimateX86/VistaUltimateX64/XpProX86/XpProX64(courtesy of TechNet)
Can run in excess of 4Ghz, but heat dump into small room (115ft^2) is atrocious! Less noise would be a plus, as well...
Problem: MOBO has heat pipe cooler on NB/SB/MOSFETs, so when I cool NB, they all have to go... Have MCH @ +.1V @ 1100 - could go higher; SB is pretty 'busy' too; normally run four demanding programs (logic controller development - video/touchscreen development - AutoCAD Electrical for schematics - Studio to develop Office/Interface 'glue') on four monitors, all cranking a half-dozen RAID disks...
Whole reason for WC is to dump the heat elsewhere! Drop from reservoir to rad/pump will be less than three feet. Am industrial systems guy, have done scads of water treatment systems - in a closed loop, gravity is negligible: the mass of the water being 'pushed up' is equal to the mass of the water 'falling'...
From feedback so far, some new info:
1x Swiftech MCP655 Water Pump - $80
1x Swiftech Radiator - MCR320 Quiet Power Res Series 120mm Heat Exchanger - $76
1x Swiftech MCRES-MICRO Rev. 2 Reservoir - $25
2x Koolance VID-385 VGA Water Block for ATI Radeon HD3850 Series - $75
1x EK-Supreme Universal Premium High Performance Water Block - Acetal - $75 (Still out on this - several people have spoken highly of Fusion - gotta look at it...)
1x EK-SB GA-X38 Northbridge Water Block - Acetal - $45
1x EK-NB/SB 5 Southbridge Water Block - Acetal - $45
1x Koolance INS-FM17 Coolant Flow Meter & Adapter Board $39 w/noz
2x Koolance Crossover SLI/xFire Slide Fitting
latest thoughts, & use finned heatsinks on MOSFETs:
Built this development system to last at least five or six years - will not be changing vid cards - proposed vid card setup:

Think this will work, as drop across each side, by definition, can't be anything but equal...
Have four fan speed monitors, w/alarms, on MOBO - will feedback the three (120 CFM+) fans, and flow meter to monitors; plan to power pump/fans from 40 watt 12VDC power supply in basement, switched by relay w/coil hooked up to machine's 12V aux supply... Won't be able to hear it if it stops - want the feedback for safety's sake!
Access to fill will be under 'built into the wall' desk in nook in corner - hard enough to deal with filling a reservoir, much less a t-line, and must be higher than highest block, so have maybe ten inches to work with... May mount on top of desk, & drill access holes through for lines...