How do I create a submit button with a mouseover image swap?
The safe (or at least much safer) way to do that is to make a markup like that dynamically generated and provide a non-scripted alternative in NOSCRIPT. Example:
<script type="text/javascript">
document.write('<a href="#" '+
'onclick="document.formName.submit(); return false" '+
'onmouseover="imageswap();" onmouseout="imageswap();">'+
'<img src="foo.gif" alt="Send" name="whatever"></a>');
</script>
<noscript><input type="submit" value="Send"></noscript>
(Of course, you can put an image submit button instead of a normal submit button into the NOSCRIPT element.)