HOW DO I: test if file exists in a template?

[ataraxia]

I'm just a novice coder and I can't seem to find an answer to this in Google or any of the XHTML sites, so please help.

Is there some bit of code that I could include in a vB3 template that would test if some particular file exists. Something like this:

<If exist ("/path/to/foo.txt")>
  do something
</if>

If this cannot be done in a template, would a PHP include do it? How would that be done?

Thanks!