my $browser = $ENV{'HTTP_USER_AGENT'};
my $explode = ($browser =~ /MSIE (\d+(?:\.\d+)?)/ && $1 >= 5);

if ($explode) {
   # print out IE5 compliant javascript code
   print "
      document.form.select.options.remove(0);
   ";
}
else {
   # print out standard (i wish) javascript code
   print "
      document.form.select.options[0] = null;
   ";
}