Delete JPG's?

[TJMcG126 9]

It varies a little one camera maker to the next, but yes there's a copy of the camera JPEG embedded in the raw file. Most commonly it is a full size JPEG. Here's a link to a utility that will extract the preview JPEG: RawPreviewExtractor Fuji is notable for reducing the size of the preview and many Fuji users will tell you they save raw+JPEG just so they can check sharpness on the camera in the field. If they save only raw files then the camera playback uses the embedded preview otherwise it uses the saved JPEG. Another difference that may show up with the embedded JPEG is the compression quality -- it could be more highly compressed than the camera's output JPEG.

I was just coming to say this (except for the Fuji part). When I look at raw files in Bridge, and I assume the same applies to Lightroom, I can see a page full of thumbnails or full-screen previews. While the embedded JPEG is likely more compressed than the camera-generated full-res version, I can assure you that the difference to the human eye would be negligible. If you're just going through looking for exposure, sharpness, composition, etc. etc., you are not likely to see any more by loading your computer with a lot of JPEGs you will never use again.