This is a very big subject and not one you can answer in a single posting. You have given very little information about your existing environment or your experience level. For example - will you be using MAK keys or KMS licensing for Windows 7? If you do not know the answer or do not understand the question, then I would recommend you download and study Microsoft's Windows Automated Installation Kit (WAIK) for Windows 7.
GSS can simplify some of the deployment issues, but you do need to have a basic knowledge of how the build process for Windows 7 works, how drivers are added and how they are detected during startup, and how you plan to handle deployment.