i googled if i can do it but to no avail the answer to the question every where was "You can divide the contents relatively easily, but the problem is that the Windows installer will still expect all of the files to be present on one disc, something you can not change. As a result, it will search for a file, not find it, and error out instead of prompting you to install Disc 2."
along with that i also read somewhere that when vista was finally released they released it in cds too so ppl with CD-ROM could get it as well so it might happen the same with windows 7.