Making an Unknown Publisher Known!

Hello all,

I have a program that I used previously on XP. As such, I trust it.

When I run it on Vista, I get the Open File - Security Warning dialog box,
that lets me know that 'the publisher could not be verified'.

I'm guessing this is because it's a guy who's just made this little program,
and hasn't certified it.

Clicking past that screen - the program works fine. I'd like to get rid of
this nagging screen for this particular program, though - since I trust this
one!

Unticking the 'always ask before opening this file' option doesn't help -
next time I click the shortcut or the program itself, up pops the box.

So - how do I make the Publisher for this program known?

J.