I just downloaded the iso files, burned the CDs and installed
Slack into my hard drive, on the 3rd 10GB partition of a 45GB
hard drive, about 32GB in.

I booted from the CD, ran fdisk to create the root and swap
partitions and marked the Linux partition as the bootable
partition.

I then did a full install, everything went without a hitch.

However when I rebooted I get a "Missing Operating System" error.

Did I miss a step or is it still necessary to install the
bootable partition in the first 1024 cylinders?

Is there a way to make the machine boot from this partition?