Gary put Windows 7 on an old XP machine. Leo says it was designed to upgrade from XP, so that should be just fine. He tried to alter the partition and now he doesn't have access to his photos. Leo says ideally, Gary should've backed up the photos first to an external drive. But once he repartitioned the hard drive, all the data was erased. There are two kinds of portioning: destructive and non-destructive. It sounds like Gary used the Windows partition utility which is destructive, and the photos have been erased. That's why backing up is so crucial.
However, all is not lost. The data may still be there. And an expert might be able to get them back. It won't be cheap, but it will be worth it. Piriform has a utility called Recuva. That could possibly retrieve them.