What to encrypt my backup external HDD with?

I have a WD Passport for a backup of my entire system.

I remove this HDD & put it away for safe keeping once the backup has been updated.

But now I want to encrypt this incase it falls into the wrong hands.

I would like 128 bit encryption & prefer to be able to just enter a password in & it unlocks the entire HDD when I plug it into any computer to access all files like a normal HDD.

What's the best program for this?

Thanks.

If you have Windows 7 Ultimate, check Bitlocker out:

Secure your USB drives with BitLocker To Go for Windows 7 | TechRepublic

Ahh I only have 7 Pro...

Truecrypt does a pretty decent job.

allend66 said:

Truecrypt does a pretty decent job.

Ok, is that really the only option if I dont have 7 Ultimate?

Just checking other options before I run Truecrypt?