I have a feeling the CD is discontinued.
Best to keep any DMG files, and I THINK you can safely download the "alternative" windows installer, but obviously not open it on a mac. What you would want to do moving from a mac to pc I don't know'
but if you save the installers to disc you should be able to transfer them. The CD if available will not have the latet version in 6 months time, and of course the basic version is availaible freeof charge anyway.