How do i encrypt/password my harddrive

[Thunderbolt]

I have a transcend hard drive that is about 500gb or so how do i password or encrypt it in a way that no one can view it without a password and that it would not cause any error on the hard drive.

[Kraminka]

I'm not sure about a whole HDD, but you can encrypt folders:

http://windows.microsoft.com/en-US/w...folder-or-file
- or -
http://windows.microsoft.com/en-US/w...folder-or-file

So, if you had all of your subfolders inside one folder, you could encrypt that.