I recently created a Windows Service using .NET, and in order to install the service, you need to execute this command:

installutil myservice.exe

However, when I did this, I received a System.BadImageFormatException. It turns out that my PATH settings were still pointing to the 1.1 .NET framework tools. Changing the PATH to point to .NET 2.0 (c:\Windows\Microsoft.Net\Framework\v2.0.50727) fixed the problem and the service can now register successfully.