I am running the Windows Vista December Community Technology Preview, which includes the .NET Framework 2.0 as part of the OS. When I try to install Visual Studio .NET 2003 on this system, setup tries to install the .NET Framework 1.1 even though .NET 2.0 is already there. Why?
Each version of the .NET Framework is designed to co-exist side-by-side with all other versions of the .NET Framework. That means you can have the .NET Framework 1.0, 1.1 and 2.0 on your system at the same time. In addition, each version of Visual Studio is tightly coupled with a specific version of the .NET Framework, and the setup for Visual Studio will always try to install the exact version it is coupled with if it is not already installed on the machine. In this scenario, the system has the .NET Framework 2.0 installed but not 1.0 or 1.1. Visual Studio .NET 2003 is coupled with .NET 1.1, so setup will install it.