DM's so right, there are some really good coolers on the market now.
I'm not au fait off-hand with the type of CPU socket on a UD2 but on my LGA 1156-based P55-US3L I've used a fanned air cooler known as the Arctic Cooling Freezer that I got from QuietPC.com and it's been simply brilliant. Okay, I never really push my PC, as I'm not into overclocking and suchlike but, if my BIOS is to be believed, my CPU core temperature never gets above 30 degrees C with this cooler. Even feeling the cooler with my hands after the PC's been on for a long time, it's barely warm.
The cooler's an 'air' type, not 'liquid'. Its full name is the Arctic Cooling Freezer 7 Pro Revn2. It costs about £15. Uses a 90mm fan. If you're canny, you can wind the revs of the fan right down to 900 rpm. (I bypass the fanspeed control in the BIOS and instead use a Fanmate to set the speed). The fan runs very quietly indeed. The multifinned heatsink itself is not so tall as to normally present any problem, width-wise, in fitting it into the PC's case.