I can't speak to Outlook 2007 but I have two methods that work with Outlook 2010. Method 1 is to simply ensure that Outlook is configured to save a copy of outgoing messages. When you want to use the message again, click on forward the message, delete the header information that will be put into the body of the message, remove the FW: from the header, change the name in the Dear XXX and you are good to go.
Method 2. Create and save a draft of your email. Open the drafts folder, highlight the message and drag it onto your desktop. You should now have a .msg file on your desktop. Make a copy of it on your desktop. Double click on the copy. It will launch Outlook and open the message to be sent. Fill in the address of the recipient and the XXX in the Dear XXX and hit send.
I am sure there are other probably better ways to do accomplish what you want, but this is what immediately came to mind when I read your post.