rolf wroteI have an Acer Aspire 5733 bought it $400 in Lebanon about 3 month ago. It's battery lasts about 2.5 hours with Windows 7, light to moderate usage (browsing and such). You can buy a battery with double (actually a bit more then double) the capacity of the original one on ebay... I guess that would give me 5 hours, and they're rather cheap ($40-$50). It should double battery life in theory. I don't see why it wouldn't work. All numbers are approximative..
Actually, as I remember correctly your laptop was using a first generation 45nm i3, which draws more power. Newer generations use less and less power. A low end i7 used to draw about 120W now it draws 77W (Will be less for laptops)
The lower the specs go, the more the battery will last, as it will draw less power. Since he won't be anything more than word processing, an Atom or a Celeron will be pretty much all he would need. The exact same laptop as you have with a Celeron processor would last more than 4 hours. With double battery, it doesn't necessarily give you double the duration. I once did an experiment on an HP dv7 i3 (Same i3 as yours) and single battery lasted about 3 hours and as for double it lasted about 4.5 hours.
rolf wroteI also have seen, not so long ago (beginning of the month), someone with weird tablet - something I never have seen before. It's a tablet attached to a keyboard. When attached together, it looks like a laptop. When detached from the keyboard, it looks like an iPad (touch screen). Both units contain a battery, so it's pretty weird, you can charge the keyboard alone while using the pad. When stuck together, the battery life is huge. I forgot the exact number, but it's at least 8 hours. Actually 12 if my memory serves me well. It's also not too expensive (but more than my laptop). Only problem: it only runs Android...!
PS: That is probably the Eee Pad Transformer TF101, that someone mentioned above
Yup that is the Transformer :P
@rahmu, You are in luck! as TPRO posted, MS Office is coming on Android and iOS ! So I guess he could just get an Eee Pad Transformer and install Office on it and he'll be on his way :D