With a little difficulty I was able to remove the air-cooling from my ATI and place this brand-new GPU block on it (between block & GPU I placed AS3 , of course!)
I then placed the motherboard into my "upgraded" Antec case, following the guidelines from the manual the installation of the CPU block was quite straightforward, I had some issues getting the Koolance temp-probe in its place, but after 2 retries I was all set.
I refilled the reservoir & noticed I didn't have enough water. Quickly ran to the local drugstore from some distilled water and 10 minutes I was testing the water circuit. I was lucky I did the test-run first, because the system was leaking all over. Seems the tubing really needs some clamps @ the connection points.. after attaching those everything was working A-OK!
Cleaning the cable mess also took me a while, but the end result is worth the effort: