As an MCT you can download all ISO images for the Microsoft Official Curriculum courses. I always found it a bit awkward that you would have to burn these to a CD-R or CD-RW before you could use it. Since I found it I’ve been using WinImage 6.1, which can be downloaded at the winimage website. This allows you to view the ISO image as if it were an actual drive with a CD-ROM that has these contents (of the ISO image) on it. It is a very good product that I can recommend to all others.
Microsoft seems to have ISO image mounting software as well, called “Virtual CDRom control panel“, as Tom Mertens tells us in one of his blogentries. It is not supported, but a free download nethertheless. You can find it here.