If you've already published your itunes podcast feed then you'll want to redirect your old podcast feed to you new sites podcast feed when you've set up the media on your site and are ready to launch it.

First upload the media you wish to feature in the new feed and customise your podcast feed.

The new public feed will be located here http://yourwebaddress/Media/rss.xml . You can redirect your current podcast feed by adding a URL redirection to your Insight website that repoints to the /Media/rss.xml address. Here's a demonstration of how to add a url redirection

Once this is done you should also look into resubmitting your podcast feed to itunes so new subscribers don't need to go through the redirect.