Ensure a FORM is submitted once

[wxdqz]

I want to ensure that a user submits a FORM only once. I do not want him to submit the same FORM twice and three times because the user is impatient. How can I do this? Also, I need to have the system recognize when he hits submit and when he hits refresh, because a refresh will re-submit the FORM.

Thanks for all the help I have received previously.
Thanks in advance.