that are real powerfull usually have short battery life. The more powerfull the components the more power needed to run them. The laptop ypour looking at has a 6 cell battery. Here's a powerfull Asus with a 8 cell ASUS G Series G71Gx-A2 which should ber a little better with battery life.

http://www.newegg.com/Product/Product.aspx?Item=N82E16834114705

This one is a a little heavy but is powerfull with a 12 cell battery. The Qosmio is a powerfull machine.