I'm using a Corsair H50 sealed liquid cooling system on my main system, which is an Intel 980X. This is the system I mainly use for transcoding and encoding video. The H50 is an all-in-one liquid cooling system that includes everything you need to go from a big, bulky air cooler to a more compact and efficient liquid cooler...but without the hassles normally associated with liquid cooling.
The H50's radiator mounts to a 120mm fan, and then you mount the fan into a standard 120mm mounting hole. You will need some clearance around the mounting area since the radiator needs clearance for the tubes. You should also use two 120mm fans in a push-pull config for maximum effectiveness. At no point do you ever need to mess around with liquids or set up a reservoir - it is all self-contained.
While the H50 may not fit into a compact HTPC case, for those of you building with larger cases the H50 is an excellent and silent way to cool even the most powerful CPUs, and you can pick one up at BestBuy for about $80.
-= SsZERO =-