The Slackware 8.1 install iso image requires 700 MByte CDR. In addition, it uses a new boot system that many systems have problems with. Either make the boot floppy and and the system disks or take a look at smart boot manager. (
http://btmgr.sourceforge.net ) Smart boot manager can be installed to floppy and when booted allow a selection to boot the CDR in drive. If yu have a fat32 partiton and can boot to straight DOS then you might also want to look at "loadlin" to load the kernel and the root system on the CD.
