Do jpeg images loose quallity everytime >the are opened and if so how much? Ang then, should I be >shooting in RAW??
Todd, as has been said, everytime a JPEG is re-saved (not just closed), you lose something... Studies have shown, if you use the EXCELLENT or highest level of SAVE then you can do a few of these without really noticing a diminution in quality.
BUT, it really is better to be shooting things like this in RAW. In RAW you can edit to your heart's content, and not lose quality.
I would recommend Nikon Capture NX2 as a fine Post-processing program. Also, View NX2 is a fine browser, and these two programs are the ONLY ones that will fully process Nikon NEFs with all the data the camera provides.