You guys are making me jealous. I wish I wasn't confining myself to the world of laptops for the next couple years :(
Like the guy said above, make sure you get one of the graphics cards that adobe endorses for the mercury engine. I'll give you a link to the list of them.
I'd also recommend getting a couple drives if you can. If I was you, I'd get a somewhat small SSD to run my OS and programs of of and then toss in some other (7200 rpm)drives to edit footage from. WD caviar blacks seem to be the ticket these days. They work in simple RAID 0 and 1 arrays, I'd opt for a RAID 0 if I was you. For backup purposes, an external drive connected via USB 3 should be just fine. If price is an issue, toss in a 1 tb caviar black for all your internal needs and have at it.
As far as RAM goes, you would probably be just fine with 8GB right now, just remember that you will probably want to spring for 16 in the next couple years.
Another idea to consider is opting for dual monitors. I just set up a second monitor, and it makes editing and general computing so much better.
GPU list and other helpful info: http://www.adobe.com/products/premiere/tech-specs.html