var snowsrc="snow.gif"
Is declaring a variable called snowsrc which is used later in the script.
You need to alter the path of snow.gif to something like
var snowsrc="../assets/snow.gif"
Or failing that replace all instances of snowsrc in the code with the full path to the graphic:
From
<img src='"+snowsrc+"' border="0">
To
<img src="http://www.yourdomain.com/assets/snow.gif" border="0">
hth
Charles
(there are only two such occurences from what can see)