Dipdude, No offense meant..I remember seeing this same info here a long time back posted by some other member..
Mod Edit : None taken - some proof would do a world lot of good.
OPTIONS (see attached image)-->crop pages--> change page size (options are 1. fixed sizes such as letter and 2. custom size, but u hve to specify the width and height.
OR
Try "margin controls"
Btw, I've adobe pro 7 with update 1.