These are what's entailed in the 4 discs:
Bootable installation disc
Bootable live disc, the Ultimate Linux rescue and demo disc!
ZipSlack, installation onto a Windows partition
Complete source code and handy Linux archives
Each are available at the ftp
But the only 1 as iso is the bootable install disc:
The other's are available in other forms and easy to obtain.
The other 2 aren't exactly available as straight up d/l's but can probably be found in various parts of the internet. Really the only 1 you'll need is one of the 2 mentioned above.