I have an excellent Sony Vaio AR series notebook and my sister wants something similar. Needs to be under �800 if poss with 2-4 Gb memory, TV card, prob Vista home premium. She uses it mainly for email, photos and basic stuff so nothing flashy in the game world needed. 17in screen would be good.
But really anything over �450 is over the top for the things your sister wants to do. My 10 year old desktop still manages to email, edit photos, browse the internet...