I have an external hard drive which i use at other peoples houses to transfer files etc. In the unfortunate event that i forget to take it home with me i'd like to secure the data as it has my documents etc on there also.

I have searched google to try to find, preferably a freeware program that will allow me to password protect the folder on the hard drive which contains all other folders. All i can find is programs that will encrypt the entire folder (currently holding around 200gb), this apears to be a lengthy and time consuming process.

All i want is for when i plug my hard drive in and click on the folder, for it to ask for a password.

Any ideas?

found this not much help really. what about this?

Or there's free trial of Lockngo

You'll be wanting truecrypt

Its free encryption software, you can even hide multiple volumes so in effect you could have one thing that looks like what you'd want encrypted (eg say your porn) and then a second hidden volume inside the first that contains your plan for world domination for instance.

So if for instance someone goes so far to kidnap you and torture you/blackmail you for the password you can give them the password to the first volume and they would have no idea of the second.

Probably complete overkill for your purposes but nevermind, you dont need to use all of its features!

Edit: btw this is military grade encryption, lose the passphrase and you can kiss the data goodbye, there is no way to recover a lost password.