The free one on iBuypower is good, its just like a high end air-cooler. Its the corsair enclosed one, I think maybe its called the H50.
Don't expect it to be like a full Liquid Cooler setup though. I'd use it if its a free upgrade.
like i said, crap, yeah its as good as a good air cooler, but if it leaks like some of the Asetek(i think this is how it is spelled) ones, you will not be happy