Help me understand this in 2007. I need to do a deployment of a large package. It could take several weeks for ALL the desktop and laptops to get this software downloaded to their computers. However I don't want the software to run until a later date. Can this be done with SCCM 2007 and can that be accomplished with setting a advertisement time and a later mandatory time. Or... when the client downloads the software while it install immediately?

Thanks

Yes. Clients will cache content for packages that are deployed to them with a mandatory schedule at the start time of the advert but of course won't execute the program until the mandatory scheduled time.