Yes, the downloaded versions are the same as the purchased versions, except you don't get the cool packaging or the satisfaction of supporting the distro.
But, before you make another coaster, what procedure are you following to burn the CD? Are you burning it in linux or windoze? And what program are you using to burn it?
The simplest way is to download the iso images from the slackware-10.0-iso/ directory of one of the mirrors, and burn those (actually, you only need the d1 ISO). But you don't want to burn a data CD that only has the slackware-10.0-install-d1.iso file on it, rather you have to create the CD from the ISO image. There are options for doing this in most graphical programs, and it is the default way to burn from the command line with cdrecord. The result will be a CD which, when mounted, will show several files, not just the single slackware-10.0-install-d1.iso.
Another thing to consider, if your CD is correct, is whether you have set the laptop's BIOS to boot from CD. Sounds silly, but lots of people forget this step.
If you're still having troubles, post back with the answers to the questions above, and I'll try to point you in the right direction. After all, us goalies have to stick together ;-)