Hard Drive Questions (mounting and purchase of)

I have two questions which I would like help with.

First one is Mac related, but anyone with Unix knowledge may be able to help. I have a hard drive which is partitioned into two: one partition is a clone of a Mac OS Installation DVD, the second partition is used for Time Machine (Backup). When plugging in the device to my computer, both partitions will mount. I would like to set it up such that only the Time Machine partition mounts and not the Installation Partition. I know I need to use fstab:

sudo pico /etc/fstab/

and to add a line to the file containing the UUID of the Installation partition plus mounting point information, but do not know what the mounting point information I should be adding is. I've done it before, but can't remember how I did it. Help appreciated.

Second question: I need a secure encrypted hard drive that is platform independent (aside from filesystem issues) and software independent. Something like the Aegis Padlock would be good, but are there any other options? Drives like this appear to be rare. This (the USB secure drive thingy) is not what I'm looking for. It doesn't have to be a high capacity drive, nor does it have to be pretty. Security and cross platform compatibility (independent of software) is key, with low cost being desirable but not necessary.

Thanks in advance.
(Hm, two questions and only one question mark in this post!)