I use the Zalman 7000 series. I have a socket 478 but they have the equivalent that fits into the 775
here. It costs about 45 dollars, and is much cheaper than the $120 dollar hsf that akherousin posted. I have a Pentium 4 2.8ghz prescott core (socket478) and it idles around 37*c and 48*c under load. Good luck and give us some updates on your decision. :thumbup:
forgot to add im overclocked to 3.0 ghz, so my temperatures are higher than usual.