Following my last post there were some comments asking questions - I'd like to make sure that anyone who might have read that post sees this & I know that not everyone reads the comments.
Syskey CAN be used to store the computer startup key on a USB token - the drivers load before the system prompts for the key - I've experience of storing the key on a USB token for both Windows XP and Server 2003. The trick is to take the option to store the key "on a floppy disk" from the interface and take the defaults - make sure your USB token is inserted once you're prompted to insert a floppy disk.
A word of caution - if your system has a floppy drive attached then the computer start up key WILL be stored on the floppy disk - if you don't insert a writable disk into the drive then you'll find that the interface goes into a loop where you're constantly prompted to enter a disk! You could of course kill the process but I don't recommend that as the results could be unpredictable.