Yeah, whats with the Windows XP and 98?
First of all.
Install the harddrive, then partition it into two 40GB sections.
Then set the boot order up so disk is the first to boot.
Insert the disk, for whichever you want to install first, Im assuming there are disks? Then install the first on the first partition which would format it in the process I hope (I'm not familiar with Unix or Linux), and the second on the second partition.