Purchase New Laptop

I need some help in the making of this purchase. Right now I own a Alienware M17 and wanting to purchase another one. I do have this one sold.

This one: i7 940XM 2.13 GHZ
8GB Dual Channel (DDR3)
SLI 1GB GTX 285M
SSD 256GB
64 bit


New one: i7 2860 QM
16GB Dual Channel DDR3 at 1600 MHZ
2GB GeForce GTX 580M
SSD 256GB
64 bit

My question is how much of an improvement will the new system have over the old one. Also, any suggestions you may have.

Thanks!