Which reference to use when operating on Excel files

I am a noob trying to enable a program to open, read, and write Excel files. I have the following installed on my computer:

Windows 7 Professional SP1

.Net Framework 4.5.2

Microsoft Visual C++ 2010 x64 Redistributable

Microsoft Visual C++ 2010 x86 Redistributable

Microsoft Windows SDK for Windows 7

SharpDevelop 5.1.0 Build 5216

Which reference should I add, Microsoft.Office.Interop.Excel 14.0.0.0 (in GAC tab) or Microsoft Excel 14.0 Object Library? 

I ask because I have tried without success to compile several different examples of interfacing with Excel and always get type matching errors or some such thing.