A channel here and there may buffer once in a while, but if you're getting choppiness across the board, there's something else going on.
You might want to give a few more details about your set-up. If you're using wireless, try hard wiring if you can to see if that makes a difference. There could be an issue with video acceleration as well, but we won't know until you fill in with some details.
Do you know the details (especially download speed) for your Internet Service plan?