Check whether or not the school offers specific configurations with discounts. Many do, and they're typically on the business lines, which you want.
For Dell, you want the Latitude line (from Small Business). The D*20 line is pretty sturdy (much better than previous latitudes). The widescreen ratio makes them better for watching movies, or for having a program open with an IM window on the side. The D620 is a 14.1" widescreen, the D820 is a 15.4" widescreen and is somewhat heavier. Both of these should be fairly cheap relative to other business grade notebooks.
Lenovo (IBM) Thinkpad T60 is probably the best built notebook out on the standard market today (there are a few that are sturdier, but we're starting to talk very expensive and appropriate for use in things like helicopters). It's a 4:3 aspect ratio, so it'll be the usual ratio. Lenovo also has the new Thinkpad Z61, which is in widescreen ratio. The T60 comes in 14.1" and 15" screen sizes (fair disclosure: I have a T60 14.1", and love it), and the Z61 comes in 14.1" and 15.4".
As mentioned above, your other option is the Intel MacBook pro. Note that there have been some serious technical issues with heat and such, which may have been fixed by now. If she's really liable to getting spyware and such (and won't particularly be able to check on it herself), then I'd suggest this, but if she's used to Windows, go for the Dell or the Thinkpad.
Regardless of the model you get, she should be getting at least a 3-4 year warranty and accidental damage protection (Complete Care from Dell, I think it's called; ThinkPad Protection from Lenovo, and there's an Apple one too). Don't go with anything less for a notebook, even though it hikes the price considerably.
A docking station also isn't a bad idea, as lazybum mentioned, though typically there won't be that many cords. Ethernet and power, obviously. A Kensington style lock isn't a bad idea- it won't stop anyone who really wants the laptop, but it may at least convince them to check the next room. Targus makes them too. Make sure to get a combination one, as the key ones are easily pickable with no significant tools. Also, a standalone mouse isn't a bad idea at all.