Index: wp-admin/network.php
===================================================================
--- wp-admin/network.php	(revision 22981)
+++ wp-admin/network.php	(working copy)
@@ -310,10 +310,12 @@
 	global $wpdb;
 
 	$hostname          = get_clean_basedomain();
+	$home_path         = get_home_path();
+
 	$slashed_home      = trailingslashit( get_option( 'home' ) );
 	$base              = parse_url( $slashed_home, PHP_URL_PATH );
-	$wp_dir_from_root  = preg_replace( '#^' . preg_quote( $_SERVER['DOCUMENT_ROOT'], '#' ) . '#', '', ABSPATH );
-	$wp_siteurl_subdir = trailingslashit( '/' . preg_replace( '#^' . preg_quote( $base, '#' ) . '#', '', $wp_dir_from_root ) );
+
+	$wp_siteurl_subdir = preg_replace( '#^' . preg_quote( $home_path, '#' ) . '#', '', ABSPATH ); // Will this work on Windows servers?
 	$rewrite_base      = ! empty( $wp_siteurl_subdir ) ? ltrim( trailingslashit( $wp_siteurl_subdir ), '/' ) : '';
 
 	$location_of_wp_config = ABSPATH;
@@ -353,9 +355,9 @@
 		<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 ( file_exists( ABSPATH . '.htaccess' ) )
+			if ( file_exists( $home_path . '.htaccess' ) )
 				printf( __( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> and <code>%s</code> files.' ), '.htaccess' );
-			elseif ( file_exists( ABSPATH . 'web.config' ) )
+			elseif ( file_exists( $home_path . 'web.config' ) )
 				printf( __( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> and <code>%s</code> files.' ), 'web.config' );
 			else
 				_e( '<strong>Caution:</strong> We recommend you back up your existing <code>wp-config.php</code> file.' );
@@ -458,7 +460,7 @@
 EOF;
 
 	?>
-		<li><p><?php printf( __( 'Add the following to your <code>web.config</code> file in <code>%s</code>, replacing other WordPress rules:' ), trailingslashit( str_replace( trailingslashit( $wp_siteurl_subdir ), '', ABSPATH ) ) ); ?></p>
+		<li><p><?php printf( __( 'Add the following to your <code>web.config</code> file in <code>%s</code>, replacing other WordPress rules:' ), $home_path ); ?></p>
 		<?php
 		if ( ! $subdomain_install && WP_CONTENT_DIR != ABSPATH . 'wp-content' )
 			echo '<p><strong>' . __('Warning:') . ' ' . __( 'Subdirectory networks may not be fully compatible with custom wp-content directories.' ) . '</strong></p>';
@@ -492,7 +494,7 @@
 EOF;
 
 		?>
-		<li><p><?php printf( __( 'Add the following to your <code>.htaccess</code> file in <code>%s</code>, replacing other WordPress rules:' ), ABSPATH ); ?></p>
+		<li><p><?php printf( __( 'Add the following to your <code>.htaccess</code> file in <code>%s</code>, replacing other WordPress rules:' ), $home_path ); ?></p>
 		<?php
 		if ( ! $subdomain_install && WP_CONTENT_DIR != ABSPATH . 'wp-content' )
 			echo '<p><strong>' . __('Warning:') . ' ' . __( 'Subdirectory networks may not be fully compatible with custom wp-content directories.' ) . '</strong></p>';