The capacity is less of an issue
Than the height. A lot of smaller laptops, including Macbooks, won't take anything bigger than 0.8" high.
Seagate is now selling 250GB laptop-friendly hard drives, including a model with integrated automatic data encryption, the company announced this week. The 250GB drive is part of Seagate's Momentus line. It spins at 5400rpm and connects to the host computer using a 3Gb/s SATA interface. They contain 8MB of cache. Seagate …
I want my disk storage, like my USB keys, as fast and dumb as possible so that encryption is totally under my control.
Anybody that trusts closed and/or unverifiable encryption schemes (whether of operating systems or of intelligent hardware) has basically abdicated responsibility for privacy. The possibilities for malfunction, backdoors and other mischief when storage media demand passwords are frightening to contemplate. We already have enough trouble convincing ourselves that our operating systems are clean without adding intelligent storage to the mix.