Security, dual boot os x partitions; making each invisible from each other?

Question

I have partitioned my Mini's hard drive with the intention of using one partition for general exploratory google surfing, and the other partition for credit card transactions, etc, thereby keeping the latter free of nasties and avoiding hacker exploits. Is it possible to set each partition up to be invisible to the other?
It occured to me another way of doing this would be to take out the mini's hard drive, put it in a bootable firewire caddy and have a second external firewire hard drive; you would simply unplug the hard drive you weren't using or, preferably, there would be some physical switch to switch between the two. I prefer simple options to configuring a firewall to the nth degree, though I should mention that I bought a netgear router that apparently has security features. I need to read up on that, too, but at the moment I am exploring my security options and firewall settings.
Any help would be much appreciated!

Answer 1

I'm not a security expert or anything, but I don't actually have a whole lot of faith in the security of the "out of the box" OS X configuration. I gather the unix bits have a pretty good track record, but some of the GUI aspects seem to reflect a lackadaisical attitude toward security. Safari's "open safe files" setting, enabled by default, has gotten Apple into trouble by exacerbating other problems on at least three separate occasions. The fact that certain areas of the "/Library" folder can be written to by an "admin", thereby affecting other users, and without the need for a password, has been exploited by iOpener in "Panther", and by "oompa-loompa" in "Tiger". You would have though once would have been enough for either of these things. "Fool me once..." "Those that fail to learn from history..." Obviously, somebody isn't getting it.
So I think you are right to be concerned. I'm not sure how I would handle the situation, but to comment on your question, it is generally considered that the best way to deal with a compromised system is to erase the hard drive and restore everything from known "good" media. Given that approach, and since you are already willing to go to the effort of creating a separate, presumably uncompromised system on an external drive for your secure transactions, why not go all the way and keep that drive disconnected when not in use? It is possible to prevent volumes from being mounted automatically at boot time (try searching for "os x" and "/etc/fstab" for example), but this won't prevent mounting if the drive is unplugged by someone and plugged in again, at which time compromised system would be able to affect the external drive. Going into more speculative territory, maybe if one boot drive was formatted HFS+ and the other UFS (OS X supposedly supports both for booting), maybe the system files required for reading the non-boot filesystem type could be removed... But keeping it unplugged would seem to be much easier, and probably safer since there would be no physical connection...
and btw, despite all the bad things I have said about Apple's apparent attitude toward security, that article you linked to is inaccurate, out-dated (ie irrelevant), sensationalistic garbage.