url function producing duplicate bits on IIS

I posted a question on this http://drupal.org/node/71277 but IIS is obviously a narrow field for drupalers!

After looking further I found some lines where $base_url was joined to url(drupal_path) I would have thought it was better to use the absolute = true option and not the base_url. I don't know if this applies to other modules and I haven't tried it on an apache set up where drupal is running in a subdirectory (all the ones I have are straight into puplic_html) but it looks a sensible change.

at line 19

//      return t("<p>In order to use this module, you need to create an account with PayPal. Also, you can setup Instant Payment Notification (IPN) to track PayPal payments from your own website. The IPN URL of your site is:</p><p><strong> %ipn_url</strong></p>", array('%ipn_url' => $base_url. url('paypal/ipn')));
      return t("<p>In order to use this module, you need to create an account with PayPal. Also, you can setup Instant Payment Notification (IPN) to track PayPal payments from your own website. The IPN URL of your site is:</p><p><strong> %ipn_url</strong></p>", array('%ipn_url' => url('paypal/ipn', NULL, NULL, true)));

and around line 123

//  $return_url = variable_get('paypal_return_url', '%order-history') == '%order-history' ? t('%order-history', array('%order-history' => url("store/history/$user->uid"))) : url(variable_get('paypal_return_url', '%order-history'));
//  $return_url = $base_url .'/'. $return_url;
//  $cancel_url = (!strstr(variable_get('paypal_cancel_url', 'node'), 'http://')) ? $base_url. '/'. variable_get("paypal_cancel_url", 'node') : variable_get("paypal_cancel_url", 'node');
  $return_url = variable_get('paypal_return_url', '%order-history') == '%order-history' ? t('%order-history', array('%order-history' => url("store/history/$user->uid", NULL, NULL, true))) : url(variable_get('paypal_return_url', '%order-history'), NULL, NULL, true);
  $cancel_url = url(variable_get("paypal_cancel_url", 'node'), NULL, NULL, true);