there are a few option, if you just want to encrypt specific data you can get a usb device with Enncrytpion ... you want hardware necryption not
software based encryption of one of these devices and certain devices claim to be a higher level of hardware encrytion than they are (256 is industry
standard for the NHS\private health comapnies etc in the UK)
if you pm me i can give you a list of decent devices for this.
if its a larger scale operation (than one mahcine) there are prodcuts that can be purchased to do it, such as SEE (Symantec Endpoint Encryption) it
also is compliant with the level of encrpytion needed in the medical records enviroment. there are other which will allow remote wiping of your device
amongst other things depends on the level\amount of money you would like to achieve.
if you were looking at your personal device againt there are products avilable which will allow you to remote wipe your device and lock out and wipe
if the passwords are wrong (again PM me if you would like to know more)
for certain files (even a large amount) i would suggest the external device option as it can then be put in a safe for added security i have both a32
gig and 500 gig device for this as i need it for work....