Either cpu is fine in your case. BUT
IF you want TURBO BOOST (over clock feature) , then you go with core i5.
For RAM, 4 gb or 6 gb is fine. Either one will do. BUT IF photoshop is going to be the most powerful program you will ever use, 4 gb is already more than enough. =D. Heck , i can run it w/o problems using 2 gb ram on a 6 yr old dumb dell desktop! Remember, you can always upgrade the ram later on =D.