The final presentation is significantly different than the interim presentation. The emphasis of this presentation is on the final product being delivered to the customer. You want to clearly explain to your audience the problem that your sponsor needed you to solve, and to what extent the system you will deliver has or has not addressed all of the needs of the sponsor.
A highlight of the presentation will be a demonstration of the working system. If this is not feasible for your particular project, you will have to use a carefully selected sequence of screen shots to give the audience a sense of what you have accomplished. You may want to weave the demonstration through the presentation, or have it self-contained at some point within your presentation. However you plan on it, make sure that you have practiced the demonstration enough to just about be able to do it in your sleep. The demonstration should flow with smooth transitions and without setup periods, or any question of how the demonstration will be driven or by whom.
Present a high-level description of the system and its architecture emphasizing why it is the best solution for this problem and the sponsor's needs. Discuss any tradeoffs you might have made in the system design. The on-line version of the book Software Engineering for Internet Applications by Andersson, Greenspun, and Grumet, has guidelines that would be applicable for your final presentation. Look in Chapter 17 Writeup for the section on Final Presentation for an idea on how to structure your talk. Adjust the times given there to cover the time period of the final presentation, as discussed below. In Chapter 6 Content Management, the section Presenting Your Work provides some guidelines for your demonstration.
You do not need to present low-level technical design details, process methodology information, or metric data. Those aspects of your project will be part of other documentation delivered to your sponsor, and be contained in the technical report you prepare.
The timing of the presentations will be strictly controlled. You will have 20 minutes for your presentation, followed by a 4 minute period for questions. The moderator will warn you of 5 minutes to go at the 15 minute mark, and 2 minutes to go at the 18 minute mark. If you run over time, the moderator will interrupt you and ask you to stop.