Should I get MacBook Pro 2011 13" or 15"?

Should I get MacBook Pro 2011 13" or 15"?
The MacBook Pro was updated in early 2011. I can afford the 17" but I will be taking this to school every day so it has to be portable. I will be running heavy Autocad, remote controller wii
, Flash, Photoshop, astronomy software+ maybe a few games. The quad core 15’ has a real graphics card. The 13" has a dual core i5 and integrated graphics. My main worry is could the 15" be too big and heavy? Could the 13" be not powerful enough? If anyone has a 15" do you find it very portable? Is the bigger size and weight and price worth the specs? What about 15" 2.0 GHz vs 2.2.GHz? Go to the apple website for full specs:

I would say “Heavy autocad” makes the “real graphic card” useful, more than 10% faster cpu.
Which card by the way ?