Drop Down List

Hello Mr Excel

I very much hope you can help me with my dilema.

I have several pull down lists in my spreadsheet.
The first list holds information on all makes of PC's. For example, IBM, Compaq Dell etc. The other lists that I have created contain PC models based on manufacturer, thus, list two is for IBM list 3 for Compaq etc. Based on the model I choose from the first list, i would like the drop down list in the next column to change so as to reflect all the pc's for that manufacturer. So for example if I choose IBM from the first list the next colum will change to display lists for all IBM models etc. Your help is greatly appreciated.

Thanks very much Mr Excel.