I found the solution to this issue in the following thread titled: [SOLVED] CentOS 6 on GA-990FXA-UD5.
The solution involved removing the BIOS RAID metadata that apparently was part of a residual software RAID that the 40GB HDD must of been used in. Running this command in the CentOS 6.5 LiveCD in a terminal fixed it:
$ dmraid -r -E /dev/sda
Do you really want to erase "pdc" ondisk metadata on /dev/sda ? [y/n] :
To which I replied "y".
This failure is a little unnerving since it occurs while running the Anaconda installer tool that's typically used by all the Redhat products (CentOS/Fedora/RHEL) and the failure is not graceful.
I'm not sure why, but Anaconda cannot deal with this situation itself, and it leaves you in a state where you can see the "verbose" debug output, which was far from helpful.
I saw no other way around the issue from within Anaconda.