Advice on what Computer to use with Pro Tools

[lorabidner]

I am buying a new computer for school (music technology) I need some advice on what kind of Mac book Pro I should buy and what (if any) upgrades I should get to make my computer run the fastest with the amount of programs I'll be using. I 'll be getting the latest Pro Tools, and loading several plug ins like "The Grand", "Halion 4" "Kontakt" and "Cinematic Strings" to my computer.I want my computer to be able to manage all of this and multi-task well. Any suggestions?

I was thinking of getting the 13.3-inch MacBook Pro 2.7GHz Dual-core Intel i5 with Retina Display with 256 GB of storage to accomadate all of the software I'll want to keep on my computer.

But what is more important for what I want to do? More Memory, Storage, or a better processor?
My budget is 1800 so It's one or the other to upgrade.

Any advice would be much appreciated!!