im a fan of the Zalman VF700-cu. As long as you have decent airflow in your case this cooler should outperform any of the Arctic Cooling ones and should be quieter too.
I realy doubt it will outperform an NV Silencer. I have a VF700-cu on my 9800XT and the Silencers will tear it up performance wise. Where as quiet goes, it has silence in its name for a reason.