Good question Dorothy.
If you have the $ or can find a good one running Windows 7 or later second-hand, I'd strongly recommend the Panasonic ToughBook.
See also this question.
Toughbooks have the following features, most of which are desirable in an orienteering environment:
3) Day-light visible display
4) Sufficient battery life to get safely through an event
5) Serial port - great for SPORTident ane Emit connectivity
6) Multiple USB ports
7) Turns into a (heavy) tablet, if you have tablet-style registration software.
8) They look like they are built by Tonka