Whether it's worth it is entirely up to you, when I did it I decided it was not and went with a sealed unit like the H55 or H110. Most people who water cool honestly do it for the videocard. It looks like NZXT made a bracket for sealed units to attach to graphics cards so IMO the incentive to do a traditional setup that is prone to leaks is just too much effort.
Most guys who do it do it out of love and anyone who says they havent lost equipment due to leaks is lying, everone does; I certianly did. I kept it around for about 6 months before giving up and going back to air/sealed units.
Now-a-days its either sub-zero or bust. Watercooling is only effective against graphics cards anymore to a meaningful effect beyond high end air cooling. These newer CPUs just cant handle high voltage long-term like they used to.
I just finished upgrading my loop and adding new controls and a new FX-8350 just yesterday. I am doing what is absolutely not being done with a factory sealed cpu loop. I'm currently at 5.17Ghz and stable running Prime95 so far over 45 min. Temps are 65c socket, 53c cores. Simply put, you can't do this with air cooling, you can't do this with a factory sealed cpu loop.
As to the OP's question about rads. I am using 2 Black Ice 50mm's. One 360 and one 120. Running NB MultiFrame Ultra Silent 2000 RPM/73 cfm fans in push/pull configuration on all rads (8 fans). Not all rads are created equal, and what is different with these Black Ice rads is how waterflow is moved within the rads. All other fans move water up, across and down. The Black Ice rads move water up the back (full width of rad) and down the front (full width of fan). What this means is the hotter inlet water cools prior to moving down the front half of the rad. This dramatically increase cooling efficiency allowing lower speed/quieter fans to perform as well as high speed/noisy fans on a different rad. It is very important to make sure you plumb them correctly however, as it is not mentioned anywhere to use the inlet port that is connected to the rearward half of the rad. If you do this backwards, if you connect the inlet going up the forward have of the rad, you will sacrifice a good bit of cooling potential as the hotter water will be transferring it's heat back to the down-flow, which has already been cooled, and then it will have to re-cool it all over again. A good way to understand this would be to consider using 2 radiators, 1 in front of the other. Plumbing the loop to the rearward radiator, then to the forward radiator would provide greater cooling efficiency then plumbing to the forward radiator first, then to the rearward radiator. The sooner you can expel the heat, the higher efficiency any cooling system will be.
The other very necessary thing is use proper heat management when considering what case, fans, fan placement, inlet/outlet placement. Heat will always want to rise so make sure you have inlet fans low or at the bottom of a case. Always place your rads high or in the top of the case and exhaust the heated air up and out. Good flow though the case of the cooler ambient air will aid cooling hot VRM's in all components and aid in overall cooling. Consider waterblocks on any high heat generating components, as it will be far better to capture that heat in your loop and exhaust it out of the rads at the top of your case. This is my setup and it is working very well. Inside case temps are only about 2c about ambient out of case temps under extended full load. There isn't much heat radiated in my case, as I have waterblocks on the CPU/Mofsest/Vrm's and GPU. 90%+ of my airflow comes in at the bottom of my case and moves up through 2-140 fans towards the rads on top and top rear. An additional 140 fan cools the HD component bay from the bottom to the top and exits in front of the top rad. This could be improved upon by creating lovers or lovers/top fan above the HD component bay, but it seems to be cooling so well, I don't believe it to be necessary.
Long answer here I know, but it is worth considering how heat moves. It will always attempt to rise, so use that in your plan. You can actually accelerate the air much easier up in a case then down. Work with the heat not against it. Pull in cool air low, exhaust hot air high.
-Rodger
