Well, you CAN buy a cert from Verisign or Thawte, and this will do
EXACTLY what you want it to do. You will get this verified trusted
certificate, then you will install it on your machine, then you will go
into the tools menu of your form, and click form options, then click
"Security" then click the checkbox at the bottom that says "Sign thi
form", Go through a little wizard, then finish and publish your form
and VIOLA! your form will be trusted and anyone can use it.
NOW.. If you wish to get a FREE certificate, you may use the
"makecert.exe" tool which will make you an unverified certificate with
which you can sign your form in the exact same manner as described
above. The only thing is, a prompt will come up the first time a user
opens the form asking them if they trust this cert. If they click no,
then they will not be able to fill out the form, if they click yes,
then the form will be just as accessable as a verisigned form.

Hope that helps,
Matt