Hmmm well having had a really good look through Scan's water cooling selection it is lacking to say the least.
If money is no object then get this,
CPU Block: Swiftech GTZ £51.10
NB Block: None Available - consider the Aquacomputer Twinplex XT £30.03 (need to check if it has any aluminium in)
GPU Block: EK FC-280 £66.99 (says it is compatible with the 280 and 260)
Pump: DDC 3.2 with XPSC Res top 18w £75.19
Radiator: TFC Triple XChanger £74.01
Barbs: TFC 3/8" Compression fittings £3.40 each (need 8 or 10 depending on NB block)
Tubing: TFC Clear tube 3/8" ID 1/2" OD £3.51 (2m length will probably need 2 lengths)
Fluid: TFC Feser One Acid green £7.04 (colour you picked, 1 will probably be enough, but having a spare is no bad idea)
Fans: 3x Scythe S-Flex 1600rpm £11.71 each
Fan Controller: Scythe Kaze Master 5.25" £34.06
MOSFET coolers: Thermalright HR09 Tyoe 2 1xU 1xS £9.98 each
Complete Total: £441.57
Cost for central parts: £253.09 - Everything that is not related directly to using a water block.
Cost to add CPU:£57.90
Cost to add NB: £56.79
Cost to add GPU: £73.79
If you decide that money is slightly more important and you would like to get a system that will cool your CPU perfectly well and not cool anything else then I would probably go for the following
CPU Block: XSPC Delta v3 £30.54
Fittings: TFC 1/2" Compression Fittings £3.51 each (6 required - Total £21.06)
Pump: DDC 3.1 10W with XSPC Res top: £62.26
Radiator: XSPC RS360 £29.36
Tubing: TFC Clear UV 1/2" ID 3/4" OD 2m length £9.39
Fluid: TFC Feser One Acid Green £7.04
Fans: 3x Scythe S-Flex 1600 rpm £35.13
Fan Controller: Scythe Kaze Master 5.25" £34.06
Total Cost: £228.84 (add £20 to get the GTZ instead)
Hope that helps, in addition I might add this (to either build)
http://www.scan.co.uk/Products/Laing...on-Damping-Kit for mounting the pump to reduce vibrations.