I waited 5 months to get back to my "mother" computer before upgrading to 5.1 because Apple told me that otherwise I would lose the original photo inventory on the ipad. So i arrived back in Greece where the Mac laptop resides, and carefully re-read the instructions. Before I installed 5.1 I had to backup. Then synching would restore all the data to the ipad. In fact, all the old photos were missing from the upgraded ipad, and only those photos from email, net downloads, or camera chip transfer remained. Apple's instructions lead one (at least me) to believe that if you undertook the suggested back up before upgrading, you would rrestore all the contents. But I am missing more than 1000 photos.