Summary: The heat sink IS very large as other reviewers have stated. It has helped drop an overheating problem I've had with an AMD Athlon 2400+ CPU from 70C-80C down to a very happy 52C-58C consistent temp, even during hot summer days.
Summary: I love it, so much more effecient than regular heat sinks. and Quiet to. My gf has the compaq x07, which is sooo loud compared to my machine, We are going to install one of these on her machine too.
Summary: Used this in my mostly silent system with the following noise reducing products. CPU is running a little warmer than before but I am a very happy with all of these products and can now work in near silence.
Summary: I installed (after some fumbling with instructions) this Bad Boy on an Athlon XP 2800 in an In Win case with an 80 mm exhaust fan. It held the CPU to 46-49 degrees C to my surprise and it is quiet. Very good solution to CPU cooling in this range.
Summary: I just installed one of these with a new Antec Super Lanboy. Awesome heatsink...My Xp2500 is OC'd a little to 2800+ speeds and my idle temps on the highest fan setting is 42c. I want a tad more airflow and a led fan so I just ordered a Thermaltake 92mm smart fan to replace the stock Zalman.
Summary: One thing about this that I didn't realise is that it is HUGE. The pictures make this thing look tiny, the heatsink is like a copper brick!! Not that I am complaining, I was just surpised at the size. Install it is a bit cumbersome having to mount the arm for the fan on the expansion card slots.