<strong>This</strong> utility that can be used to quickly switch the .NET Framework version that the aspx pages are compiled against.I am not sure why you would want to run both the versions of ASP.NET on the same box at the same time as 1.1 is backward compatible to 1.0, but I am sure there are many reasons which make total sense - I just cannot fanthom any at this time. Internally, it uses the command line tool called ASPNET_REGIIS that is included in the Microsoft.NET Framework.