Click the Toolbox button on the form design toolbar. From the toolbox, drag a combo box to your form. On that control's Properties dialog, on the Value tab, you can set it to be bound to an Outlook property and can also set the Possible Values property of the control.
FYI, there is a newsgroup specifically for Outlook forms issues "down the hall" at microsoft.public.outlook.program_forms or, via web interface, at http://www.microsoft.com/office/community/en-us/default.mspx?dg=microsoft.public
.outlook.program_forms

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Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx
>I am trying to personalise the "Contact" form in Outlook, bu inserting a
> field which will then have a drop down box with values in it to choose from.
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>
> I want to create a user defined one of these...with my own values in