Macro to provide list of alternatives based on cell value

Hi,

I am trying to provide a drop down list of alternatives from another worksheet based on a cell value. I have attached a basic workbook to explain further.
I have created a form into which a user must enter a postal code. This postal code may have a number of different alternatives:,
eg: Postal code 4000 may belong to the following areas: Perth,Perth West,South Perth,North Perth.

What I would like to do is present the user with the 4 alternatives so that they can choose the correct area. I am thinking that I will need a macro to do this. If anyone has any suggestions it would be most welcome.

Thank you for your help.

Wayne

Thank you so much for your response and help, it is very much appreciated.