Modifty MAIL.oft file for Outlook 2007

I want to modify my default new message mail window to have another textbox field. I do this by going to Tools -> Forms -> Design a Form. From the 'Standard Form Library' I select 'message' then 'open'. I add a textbox and label and name them. Then I select File-Save As and give the name MAIL.OFT and save it in C:\Program Files\Microsoft Office 2007\Templates\1033 where the original file was. However when I close the From designer and click the New Mail Message icon the original form is still being displayed. I can't understand this! Can anyone advise me on this please. Thanks.

[648 byte] By [RudolphScott] at [2008-1-9]