It really all depends on the price and the specs. Laptops that are named "powerbook G4" actually span a VERY large range of different models over MANY years and many different levels of technology. I wouldn't consider spending any hundreds of dollars on a PB G4 that's earlier than a 1.5 GHz model, or maybe even a 1.33 GHz if you can get some sort of insanely cheap price on it. But if you can find a 1.5 GHz or faster PB G4 that's in very good condition with a brand new battery and maxed out RAM, then I would say that you should spend a MAXIMUM of $300 on it, but I'd say even that's pushing it.
I know of what I speak - I'm typing this on an Aluminum PB G4 1 Ghz right now. It has been downgraded to kitchen surfing duty only. Its battery hold about 30 seconds worth of power, the screen has grown very dim and yellow over time, the command key on the left side just cracked right in half, it's gone through a couple of charging cables that seem to die after 2 or 3 years, etc. I mean, this machine was a true workhorse for its day, and it was built like a tank, but after 8 years or so, time takes its toll and technology marches ever onward. I'm very happy to have this PB G4 1 GHz around as a light duty entertainment machine around the house, and it's still super useful in many way. But just like an old car, at some point you have to decide that it's not worth the money to repair it anymore and that your dollars would be better spent saving up for a new (or newer used) car.
You said:
She will use this mainly for email, web, facebook, (facebook games), YouTube, etc.
For those tasks, once you start to get into the over $300 range for buying a device, I'd suggest that a $500 iPad would be money much better spent for a light duty entertainment machine. She wouldn't be able to play flash games, but overall I would guess that she'd get a lot more entertainment out of the iPad.
It's 15 or 17", DDR2 or DDR one?
