Muscle gain vs fat loss

I am interested in others experiences with excerise programs that burn fat and build muscle. I am doing P90X and so far after phase 1 have lost around 5lbs and am feeling great. If I wasn't doing P90X I would aim for a weight around 165-170 - I am guessing I will wind up a little north of that but not sure what a reasonable expectation might be. I realize this is a totally impossible question to answer specifically for me, but examples of others experience would be useful.