Installation ISO disc 1
Installation ISO disc 2 (GNOME/KDE/KDEI, /testing)
ISO disc 3 (Sources part 1, /extra , Slackware book)
ISO disc 4 (Sources part 2, ZipSlack, /pasture)
You could just donwload disc 1 but then you'll have to use fluxbox or some other window manager becuase gnome and kde are on disk 2.
Solution to this will minimizing the stuff is just download disk 1 and if you want kde just download the individual packages at
you need kdebase-3.2.3-i486-1, kdelibs-3.2.3-i486-1, and qt-3.3.2-i486-2 packages in the kde section for a minimal kde. I think this would be the best way to go for you. If you really wanted to go with gnome you'd be better off just downloading the entire cd 2 becuase you need practically all the packages in gnome to get it to work, unfortantely. kde is nice though, i use it myself along with fluxbox and directfb.
Disk 3 and 4 are the source code to linux. it also has the testing 2.6.10 kernel in there but since you are on dialup if your really wanted to test it out just download the source at kernel.org and build it yourself. will save a lot of bandwiddth. otherwise, just stick with the 2.4.29 kernel which is on disc 1 and the default for slack.