Password Protectio

Hi folks,

I’ve got a 250Gb WD MyBook, its about 3 or 4 years old now but still going strong. I was wondering if someone could tell me the best way to put password protect on the hard drive. Does WD provide free downloadable software for this? I’ve heard there are various free third-party options, but I’m not sure which one’s are good and can trust be trusted. 

I wondered about changing the permission settings (via Vista) but I’m not sure if that would just change access whilst on my main laptop, and not on other computers (which would be a bit useless).

Thanks for any suggestions,