You can get quad core, but only in the 15" and big money. I can guarantee you will not be disappointed with the performance. If you can swing it, I’d say go for an SSD. Between the i7 dual, SSD and 8GB of memory the laptop would blow your mind.
Also, look into the Air’s as well. They all come with an SSD out of the gate. I have the 11" model with i7 2.0ghz, 256gb SSD and 8GB of memory and it does everything I throw at it. Even the i5 Air will perform well and the battery life it ridiculous.
How intense do you use Photoshop? Are you running like hard core filters and things that really toll the processor or just normal stuff?
Also, get an educational discount. Makes a nice difference. Even if you’re not currently a student, just show a college ID. No id, I’ll purchase it for you with your payment of course. Lol