First Mac! Which MBP with Which Specs for Logic?

Hi! I am a musician and want to get into recording. Fellow music friends have convinced me Logic is the way to go, so after over 15 years of windows, I am purchasing my first mac!
While this is exciting, I do not know which one to get. I have read the many MBP 13 vs 15 threads but have found nothing for how the spec differences will affect music recording using logic. I have heard that screen size makes a huge difference, but I am also a traveling student and this will most likely be my primary laptop for school, work, etc. T

That said, I am willing to drop some serious cash if a case can be made that upgrades, new processor, etc are really worth it. So basically, which MBP is the best bang for your buck regarding logic? Also, would it be worth it to upgrade to SSD? I understand using a 7200RPM external firewire drive is ideal and I will invest in this for backup, but perhaps a SSD for current projects would be good?

I'm open to all models (even the 17") but just don't know if it will be worth it for Logic. Is screen size that important in Logic? Will the new processors drastically boost performance and make the MBP hold its dollar value longer? Help!

Right now, this is what I'm leaning towards:

13" MBP 2.4Ghz C2D
4GB Ram
128GB SSD
$1480 Canadian (minus "free ipod touch" if I sell it) = $1280 CD

Additionally, I would buy a cheap external monitor and large external 7200RPM firewire drive.