©  2006,  Australian  Computer  Society,  Inc.    This  paper  appeared  at  the  Seventh  Australasian  User  Interface  Conference  (AUIC2006),  Hobart,  Australia.    Conferences  in  Research  and  Practice  in  Information  Technology  (CRPIT),  Vol. 50. Wayne Piekarski, Ed. Reproduction for academic, not-for profit purposes permitted provided this text is included.