I3 vs. i7 battery life

[boredpessimist]

I am currently looking at two comparable notebooks featuring an i3 and i7 processor respectively. My gut is to snag the i7 for the good price but I am worried that the battery life might be insufferably short if I do this(I am not current on chip technology and I remeber previous generations of chips where the performance lines would produce battery lives of barely over an hour)
Anyway I was wondering if anyone could give me some insight into what the difference in battery life would be for an Intel® Core™ i3-330M Processor 2.13GHz 1066MHz 3MB and or an Intel® Core™ i7-720QM Processor 2.80GHz 1333MHz 6MB if they were on a comparable platform?

Also, on a tangent, is $750 a decent price for a nicely equipped laptop with the i7 from above paired with a gt240?

 

[buwish]

Besides the processor, battery life is dependent on other hardware options in the computer. In regard to the i7, I've seen reports of battery life from a little over an hour to 3 hours, so it varies. I would assume that the i3 is along the same lines, i.e. same technology, but may potentially last longer. You might as well snag the laptop with the i7 and gt240, as that isn't a bad deal at all.