WP_CodeShield

This plugin escapes all text inside code tags so you don’t have to worry about converting code to HTML characters (e.g. >‘s to >‘s). The contents of code tags inside posts and comments are run through php’s htmlspecialchars.

1. Unzip wp_codeshield.zip.
2. Upload wp_codeshield.php to wp-content/plugins.
3. Activate in the Plugins menu.