I don't believe Bridge makes any use of the embedded Jpg. I"m still not quite sure at what point, from the original description of the problem, where the problem is occurring. Are you all in Bridge, and click to see the Preview (not a zoom), or are you actually in the RAW converter and you zoom and see the problem?
Just as a side note, I have CS3 and I shoot with the Canon 20D and thus have CR2 files. I have never noticed the problem you all are talking about. Perhaps you could post one of the CR2 images that you're having a problem with.
"The map is not the Territory"