You can set it up manually to automatically send the e-mail every week.
Open a new email, select Options in the Send Toolbar then check the Do not deliver before box. Select the first week's date from the calendar when you want the first mail to go out (and optionally change the time to whatever time that day that you want). Enter the text that you want and send the mail. It will remain in your Outbox until the specified time of delivery. Just repeat this for each week, selecting another week each time. You can do this for as many weeks as you like in advance. It will take but a few minutes one time and it will all be automatically handled thereafter.
You could also add the text to AutoText (when using WORD as the Outlook editor) and insert it so that you don't have to type it in each time (in the Normal field), add it as an Autotext subject and dispense with text completely, or just copy and paste it from the first email to each succesive one.