I'm on a Mac OS 10.6.8 "snow leopard". I have Photoshop CS3 extended that I purchased in 2007. I'd like to upgrade to the latest version of photoshop. What OS will I need to upgrade to first and what is the lastest photoshop? I realize I will probably have to purchase the new photoshop since mine is so old. Will my my files that I use now be available to me?