Bascially, if you open up Control Panel >> Administrative Tools >> Internet Information
Services you can create sub-sites under the main default site. These are fully functional websites and will be accessed in your browser at http:// localhost/ subweb-name or by right clicking on the site in the left panel of the Internet Information
Services applet and selecting the option to "Browse" the site.
Your test sites may include various permissions to run certain scripts and you can configure them to do all sorts of things, or not as the case may be.
FrontPage can publish direct to your IIS directory for testing and this is a perfect scenario for testing your FrontPage sites. This is especially true when using the FrontPage database interface since you can locally publish the site and its database and IIS will serve the pages to your browser just as they would be served by a web host (more or less). When using ASP, .NET and other dynamic languages this allows you to test and debug your web applications without having to constantly upload and download to your web host.
The only exception to that rule is any web based email applications, since setting up the SMTP server on a local IIS installation gets a bit involved and is of little value to most users.
Since IIS supports FrontPage Server Extensions (with a tiny bit of configuring) you can use FrontPage to your hearts content.
You can also install PHP and MySQL into IIS, but we'll leave that for now I think.