Furthermore, in most cases it is not necessary to download all of the images for your architecture. The packages on the CDs are sorted by popularity: CD 1 contains the installation system and the most popular packages. CD 2 contains slightly less popular ones, CD 3 even less popular ones, etc. You will probably not need CD 3 and higher unless you have very special requirements. (And in case you happen to need a package later on which is not on one of the CDs you downloaded, you can always install that package directly from the Internet.)