[faint545]

I've used the Zalman and from my personal experience, I really liked it. Only reason i'm not using it anymore is because I lost the bracket for my AMD socket and I didn't feel like spending another $40 or so just for a bracket.

Either one would work just fine, although from what I've researched on the internet, the Zalman cools a bit better but don't just rely on my opinion; research it for yourself. However in my opinion, if you're going to be overclocking, I would get the Zalman. Otherwise you can just go for the Zen or even, the stock heat sink & fan.