Visual InterDev
You can create files in Site Designer without regard to the file type and then you can convert individual ASP pages to HTML pages as needed.
To convert ASP pages to HTML pages
Select the .asp file in the Project Explorer that you want to convert.
Right-click the page, and choose Rename from the shortcut menu.
Note The Rename command is available for local files only.
Change the .asp extension to .htm.
Press Enter.
In the message box, click OK
In the Link Repair dialog box, click Yes.
The .asp file icon is replaced with the appropriate .htm file icon in the Project Explorer.