If you're looking at 3D development work you're not really going to get that much life from any battery really so I'd look at other features. If the 9600 is the same price as the 8600 recheck the specs to make sure they've not limited features to keep the price the same.
I did some more reading tonight, and I am wondering if the HP dv5t might be a better buy. Apparently the CPU chipset is newer, and the 9600 GT outclasses the 8600 GT in the Dell. Pricing seems comparable. Then again, I'm worried that the 512 MB video card might put greater strain on the battery. Maybe I should look at a…