UPDATE:
After updating to 10.6.7, the choppiness returned. I am now convinced 10.6.7 is not optimized.
To all who posted here with no problems, did you update to 10.6.7?
Yeah, mine works fine. And Apple stores are always on the latest OS, so I'm beginning to thing it's your internet connection. Take your laptop to starbucks or apple store and connect to their internet and see if it does it.