According to Google's Webmaster tools, there are about 15,000 incoming links to my site. 13,000 of those reference a .ASPX file on disk. When I convert to MVC, with new Search Engine Friendly urls, all those links will break unless I do something about it. Presenting users with a 404 - file not found is not an option. I need to show them the content they were expecting, and update Search Engines with the news that things have changed. Here's how I will be managing those Legacy URLs.