Changing permissions of an entire external drive and all of it's subfolders

Essentially, I need to take ownership along with read/write access to all files and folders on a particular volume, external in this case. I've copied files from other machines I've owned in the past that were stored on them and consolidated them all to one external drive. I now need to be able to read/write all files/folders on that external drive and thus need to find a reliable and reasonably efficient way of doing so.

I've tried the Get Info > Sharing and Permissions business but it never seems to actually apply to the folders in it. I've heard about Chown but am not sure about how reliable that is or even if my terminology is right. I'm not afraid of terminal but will need to know what commands need to be entered. I also am not afraid of disk utility.

Any good ideas?