I am running the Mint Live Cd right now and here is the output of the fdisk command relating to the third drive.
Disk /dev/hdh: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/hdh1 1 3264 26218048+ 83 Linux
/dev/hdh2 3265 6528 26218080 83 Linux
/dev/hdh3 6529 9725 25679902+ 83 Linux
/dev/hdh4 9726 9729 32130 83 Linux
I can also 'see' this drive in the partitioner when doing the install, but when you get to the point of assigning mount points I can not select any of the partitions on hdh.
With the four connections on the motherboard (at tow drives each) this is the equivalent of being the eighth drive in the system. It is the slave drive on the last connector. I don't know what the limit of the installer is.
Anyway, I have freed some space on the first drive in my system and will install Mint there. Hopefully a solution can be found so that someone else doesn't get to that point in the installation process to find out that the drive space they want to use is not available for selection.
Thank you for your reply.