How to force an application to use .NET 3.5 or above?

Question

Our application is built with VS 2008, uses Linq and has Target Framework set to .NET Framework3.5.

It works OK when only .NET 3.5 or 4 is installed on the machine.<

Answer 1

Another useful link is this page on MSDN. This shows all of the values required in app.config if you want to just target the client profile or if you require the full profile.