I'm having the same exact problem--it's more than a mild annoyance, and I can't seem to find any solution. Streaming Internet audio (YouTube, movie trailers, etc.) clicks and pops as it struggles to keep up. I'd normally guess that this is a system resources issue, but my MacBook Pro has 4G of RAM and a 2.2Ghz Intel Duo, and it occurs even when I'm not running any other apps...