Go ahead and give your deployment project a shot. It is also helpful because if you compile, say, a .NET 3.5 application and they don't have the framework installed then the application will just crash and you can't even show an error message box saying what the problem is. With installers you have launch conditions. One added for you by default is for the .NET framework.
There are a couple of tricky ways to do what you're asking but they have a negative performance impact and sometimes trigger false-positives on AntiVirus due to the nature of how they work.
Hello tiwas,Sknake is right
No need to include any dll with your project, when you made your setup, you selected primary output in that, that primary output include all dll of your project and a setup file, when you install your application on user end..........:)