I was actually looking into what it would take to do something like this. Not a daughter card, but through a diskcrypt-type software using a 1024 bit key on a USB keychain. Supposedly you can mount and unmount a whole drive with a command. Use the key while doing this...
However, one of my caveats would be that the disk would have to re-encrypt after an hour of non-use. After all, when they bust your door down, will you have time to turn the PC off? This motherboard they're selling is only going to keep you safe if you're machine is off. If your machine is already off, then you might as well put your hard disks into the ceiling vents.
Some might argue that most agents would bust down your door, and just confiscate your computer. But I am sure that they would be keeping an eye out for these type of motherboards, and more likely do a check before turning your computer off.
Oh, and last but not least... You have to have that USB key hidden. And I think they'd even check your ass. So how exactly do you hide the keychain in a difficult place to find-- but not so difficult that it's a hassle to you too (because if it is a hassle, then you'll just leave your computer on all the time...thus unencrypted)
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However, one of my caveats would be that the disk would have to re-encrypt after an hour of non-use. After all, when they bust your door down, will you have time to turn the PC off? This motherboard they're selling is only going to keep you safe if you're machine is off. If your machine is already off, then you might as well put your hard disks into the ceiling vents.
Some might argue that most agents would bust down your door, and just confiscate your computer. But I am sure that they would be keeping an eye out for these type of motherboards, and more likely do a check before turning your computer off.
Oh, and last but not least... You have to have that USB key hidden. And I think they'd even check your ass. So how exactly do you hide the keychain in a difficult place to find-- but not so difficult that it's a hassle to you too (because if it is a hassle, then you'll just leave your computer on all the time...thus unencrypted)