Let's start by looking at the business drivers.
It may be an obvious point to make, but the key to identifying the business drivers is to really understand what you want to evaluate. By this, we mean is it a strategic decision based on the need to transform your organization with new working initiatives, or is there a more compelling event, such as the end of life of an operating system or application? It may simply be the need to reduce cost.
Whatever the case, you need to get that nailed down and written up on day one so the project has meaning and direction, and more importantly a baseline to refer back to when it comes to review time to gauge whether or not the project has been successful.
Primary drivers include things such as:
Cost reduction – operating expenditure