I'd include a project plan.  It doesn't have to be complicated, but it should include things you've left out that will be helpful to you and to management.

• Scope: What's included in this Altiris project?  What's not?  This is a good chance for you and management to be in agreement on what will be done.
• Deliverables: What are the deliverables of each of the features you're including?
• Project Workplan: Doesn't have to be complicated.  It sounds like you have a project timeline, which I assume is based on a workplan you've developed.  The workplan would be what built the timeline by mapping out tasks for the project and the time you estimate each will take.  Remember that you're not always 100% available due to illness, your manager's pet projects, interruptions, etc.  If your timeline wasn't based on something solid like a workplan, it may not be very valuable.
• Assumptions: Be sure to list any assumptions you're making.  Assumptions are the things you'd like to know for sure, but can't.  For example, an assumption I made on a recent project plan is that moving databases for custom webpages from a SQL 2000 server to a SQL 2008 server won't affect the pages.  I'd like to know for sure, but the time to set up a test environment is too expensive, so we're making an assumption.
• Budget: Be sure to mention any budget requirements you have, such as money required for training or server hardware.
• Resources: List your resources.  Is it just you, or are you going to require effort from your network administrator and database administrator?  What about resources outside your department, such as end-users in a pilot group for testing, or graphic designers for branding your portal?

So far, you've primarily focused on the technical.  The project timeline you've already created along with the items I've listed above should help you plan your project and communicate it to management.