Index: wp-admin/install.php
===================================================================
--- wp-admin/install.php	(revision 29709)
+++ wp-admin/install.php	(working copy)
@@ -118,7 +118,7 @@
 				echo '<input name="user_name" type="hidden" value="admin" />';
 			} else {
 				?><input name="user_name" type="text" id="user_login" size="25" value="<?php echo esc_attr( sanitize_user( $user_name, true ) ); ?>" />
-				<p><?php _e( 'Usernames can have only alphanumeric characters, spaces, underscores, hyphens, periods and the @ symbol.' ); ?></p>
+				<p><?php _e( 'Username can have only alphanumeric characters, spaces, underscores, hyphens, periods and the @ symbol.' ); ?></p>
 			<?php
 			} ?>
 			</td>