my $path="http://servername.com/username/images/";
my $imagename="filename.jpg";
my $imagedefault="default.jpg";

if ( -e '$path.$imagename'){
print "<"."code><td><IMG SRC=."$path.$imagename."></td></code".">";
}
else
{
print "<" . "code><td><IMG SRC=".$path.$imagedefault."></td></code" .">";
}