I hadn't made a custom one and set a bunch of redirects in htaccess. Well it turns out I was get server 500 errors if something wasnt found rather than redirecting to the homepage (which isnt good either). No I have a successful 404 page and it has a delayed redirect to my main page. How important do you think this is to prevent the crawlers from seeing errored pages and duplicate content? Very important? Or not so much?