I'm assuming you've seen this documentation about how to properly use Visual Studio with Unity C#: http://docs.unity3d.com/Documentation/Manual/VisualStudioIntegration.html
Verify if you're using VS Express or Professional.
My only suggestion would be to retry those steps for your project, or look into acquiring UnityVS. UnityVS is an asset package that you import into your Unity project, and it allows you to use Visual Studio's Debugger with Unity.
Alternatively, Sublime Text Editor has beautiful syntax highlighting for Unity C#, but does not compile or debug your code.
Best of luck.