would love to lol, but there are the usual questions / paramaters. (i'm guessing that this is a gaming computer in a reasonable case).
if you have a closed case, with no windows, with a fan front and back - the Zalman CNPS9500 AT. a cheap, quiet and powerful solution.
(heres a shot of a 9700LED i put in a mates case. they look almost identical to the 9500)
if you have a window in your case and you want to be a little fancy - the Thermaltake Blue Orb FX is nice unit that even tells you the case temprature.
ADF Macca has one of these bad boys.
if you have a windowed case, deep pockets and want to over clock the ass off the cpu - Thermalright TRUE Copper Limited Edition
just love the look and performance of these

hope i've helped