.NET 1.1 applications on IIS7

Vista is finally here and so is IIS7. It might be time to port some old .NET 1.1 applications over to IIS7 but sometimes you may run into problems like "page cannot be displayed" or other errors.
Most errors can be solved by changing default application pool and allowing .NET 1.1 extensibility on ISAPI and CGI restrictions.
However if you still cannot get your application default page to display, check if .NET framework 1.1 service pack 1 is installed on that machine? The SP1 adds support for Vista/Longhorn.