Start at the Cnet Laptop Buying Advice Forum and it's top post at:
Laptops are rarely expandable, maybe RAM and maybe the hard disk size but not much past that.
Battery life in the 700 range is usually the 300 cycle or the 1 to 2 year battery.
I barely know where to begin. I want one that's light, fast, and doesn't get hot. I prefer Intel, 3-4GB ram, plenty of memory, 14-16 inch display, DVD burning optical drive, Windows 7, good battery life, and endurance. I'd rather spend less than $700.
I don't do fancy photo or video or presentation stuff; this is for home use but with capacity to expand if necessary - who knows what tomorrow will bring?