Hi mepossem
You just need to set a template and recall it everytime you want to attach a file to the message here's what to do.Hope it works
Send an e-mail message based upon a template

You can use e-mail templates to send messages that include information that doesn't change from message to message. You can compose and save a message as a template and reuse it when you need it. You can also add any new information before sending the template as an e-mail message.
Tip In addition to your own templates, you can download Microsoft Office Outlook 2007 templates on Office Online.

Create a template
1. On the File menu, point to New, and then click Mail Message.
Keyboard shortcut To create a new e-mail message, press Ctrl+Shift+M.
2. In the message body, enter the content you want.
3. In the message window, click the Microsoft Office Button , and then click Save As.
4. In the Save As dialog box, in the Save as type list, click Outlook Template.
5. In the File name box, type a name for your template, and then click Save.
By default templates are saved in the following folders:
Windows Vista c:\users\username\appdata\roaming\microsoft\templa tes
Microsoft Windows XP c:\documents and settings\username\application data\microsoft\templates

Send an e-mail message based on a template
1. On the Tools menu, point to Forms, and then click Choose Form.
2. In the Choose Form dialog box, in Look In, click User Templates in File System.
The default templates folder is opened. The folder location is as follows:
Windows Vista c:\users\username\appdata\roaming\microsoft\templa tes
Microsoft Windows XP c:\documents and settings\username\application data\microsoft\templates
If your template is saved in a different folder, click Browse, and then select the template.
3. Select the template, and then click Open.
Select the template you want to use.
Click Open to proceed.

4. Make any additions or revisions to the recipients in the To, Cc, or Bcc box, Subject, or message body that you want.
Note Changes you make are not saved to the template. If you use the Save command, this will create a draft of your message but will not update the template. To update the template, use the steps in the prior section Create a template, beginning with step 3.
5. Click Send.
For Further queries feel free to ask
~Dex