Most desktop PCs don’t have the ability to set an ATA password in the BIOS, precluding you from enabling the onboard AES-128 encryption in a drive like the Intel 320 SSD.
If you’re willing to hack your BIOS or burn a boot ROM to put in a network card, Arne Fitzenreiter has ATA Security eXtension (ATASX, or ATA SX)–a way for you to add that support to computers that lack it.
Seeing as most people don’t have the ability to burn a boot ROM to put in a network card, that leaves modifying a BIOS image and writing it to the motherboard as the most viable option for the majority. That isn’t a casual modification, and it carries the risk of turning your motherboard into a brick if something goes wrong. As I don’t have an Intel 320 yet (I’m still rocking OCZ Vertex SSDs, personally), I haven’t had the need to experiment with this yet. I would suggest you practice by modifying whatever motherboards you have collecting dust in the corner before you do this to your everyday motherboard.
If your motherboard has a built-in NIC, this safer (but still tricky) method may work for you.
Of course the ideal thing would be for desktop motherboards to start supporting the ATA password from the factory. Until that happens, this option is better than nothing, for the brave and daring.
I much prefer to write about things I’ve actually tried myself, but seeing as AES-128 and Intel SSDs seem to be the topic of the year around here, this may be useful to someone.