Index: wp-admin/network.php
===================================================================
--- wp-admin/network.php	(revision 16879)
+++ wp-admin/network.php	(working copy)
@@ -336,10 +336,12 @@
 		<h3><?php esc_html_e( 'Enabling the Network' ); ?></h3>
 		<p><?php _e( 'Complete the following steps to enable the features for creating a network of sites.' ); ?></p>
 		<div class="updated inline"><p><?php
-			if ( iis7_supports_permalinks() )
+			if ( file_exists( ABSPATH . '.htaccess' ) )
+				_e( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> and <code>.htaccess</code> files.' );
+			elseif ( file_exists( ABSPATH . 'web.config' ) )
+				_e( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> and <code>web.config</code> files.' );
+			else
 				_e( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> file.' );
-			else
-				_e( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> and <code>.htaccess</code> files.' );
 		?></p></div>
 <?php
 	}