What operating system are you trying to use to mount this unformatted disc?
If you are using Linux then when you load the disk tell automount that you do not want to mount this disc and to leave it unmounted. You can then partition the unmounted disc using fdisk or parted.
If you are using Windows then I suggest that you don't bother with Windows. You can partition and format the external disc using the Linux installer. Plug the external disc in and then boot your Linux install CD. The installer should find all of your devices which are plugged in and turned on. Then you can use the installer to partition the external drive, format the partitions, and install Linux to the newly formatted partitions.
P.S. If you have further questions please tell us what distribution of Linux you want to install. Install procedures vary somewhat among distributions.
Last edited by jailbait; 08-25-2008 at 08:27 PM.