[jQuery] Manipulating form field attributes

Hi everyone,
I'm trying to use the following code to change <input type="text" />
to <input type="hidden" /> where the element has the classname
"navtitle".
    $(".navtitle").each(function() {
        this.type = "hidden";
    });
This code works fine in Firefox but has no effect at all in IE. Can
anyone help me please?
Sam Hastings