To do it properly (i.e. CPU, motherboard, GPU and HDD) about £200+, plus you might have to cut/drill holes in your case. Its almost silent - the pump runs at a few decibles - certainly no more noisy than a DVD spinning up.What sort of cost is involved with that and is it worth the hassle ??
If the PC is staying static, and not being shifted about the house it can be worth the effort. The water and copper alloy blocks aren't light if you're going to lug it from room to room. You need to keep an eye on the fluid levels and top-up every week or so for the first few months. After that you shouldn't have to top up more than every 6 months, just don't forget!
I will point out that my mate has lost a motherboard and a £300 graphics card due to a leak before today.
I did read the info regarding fans for that case and know which ones will fit, but if there is a different brand like you said earlier that is quieter it is worth looking at. As for overclocking, i like the idea of it but rarely bother, however with this one if its a case of just upping something simple in the bios then i more than likely will, im not that involved that i would want to start going into great detail and things liike adding cooling to the ram etc etc.
If you want a zalman cooler, get a zalman cooler. Just use the included fan mate 2 controller if its too noisy - I should have said that to start with.
Also plan your air flow, front to rear is best practice. Don't be affraid to turn a case fan round bacause its blowing the 'wrong' way.