water coolin is kick ass but only if u got the $. as far as what heatsink is best it depends on wether u are using a p4 or an athlon. the athlon's best sink is the thermalright slk-800, i havent seen one review that it didnt take 1st place on. and you can pair it up with any type of fan you want, 60,70, or 80mm. when you choose the fan you should determine how loud u can stand it, and remeber the decibel scale is not linear so 50dba is not twice as loud as 25dba, its way louder, in fact unbearably loud. 25dba is so quiet you probably wouldnt even hear it inside the case in most situations. anything over mid 30's is loud.
here it is
<A HREF="http://www.hardocp.com/article.html?art=MzE3LDI=" target="_new">http://www.hardocp.com/article.html?art=MzE3LDI=</A>
P4's are good to pee on.