Display most current published file

Users download Data Dictionary (.chm) from web site. Want to let them know that the version they are using is not the most current, automatically without user action. Currently, I have a hyperlink to an ASP page that will display the most current version. Would like to develop something similar to some applications. That is, when app starts, it tells you that updates are available. Or, I would like to automatically display the ASP in the page of the .chm without user action.