if it's the same as when I did it make sure you read the stuff they send you as the written paper is likely to refer to it...
good luck!
one thing I forgot:
one of the papers requires answers to math type questions, you have a fixed time but try and answer as many as possible as I was told after the event that there was a cutoff point on the paper...ie, if you had not progressed beyond the cutoff point, you were out, no matter how many you had answered correctly!
[This message has been edited by bill (edited 12 August 1999).]