For laptops/notbooks i would rather go down the road of Apple Macbook pros, but thats just me, since i study IT and needs Unix environment handy, long battery life and good screen. so i got my self a 15" MacBook Pro just few days ago and so far its a great investment. (sure i could of done with Linux but i needed photo editing and few other programs that Linux don't supply)
first things the budget, 15" can be hunted from $500 to $3000,
what sort of programs does she need to use for Uni?? any spesific programs?
I'm guessing from Geology/Physics/Math, might be needing processing power and some sort of dedicated Graphics to support CAD and other physics needs.
from what i can see in windows world, Dell, ASUS, HP, Toshiba should and some already has Sandy Bridge Laptops out, look for 15 or 17 with model number starting from 2XXX, much RAM as you can get 4GB minimum, 8GB better.
Dual, Quad CPU, depending on the Needs, again it depends on the needs and budget.
from "as high performance as possible, without being silly about it." then i would go for the Dell's New XPS 15.6"
. just because the price is reasonable, has all the bits and i guess it has better warranty handing than other company i used. actuary this was my second choice in PC when i was choosing my laptop.
i'm sure once we know what sort of Application she uses then we can suggest bit more.