Thanks. That was the answer I couldn't find.

*RANT MODE ON* I had assumed that Knoppix used Unix conventions, and that making a volume's user/group/world permissions r-w-x enabled, that would in fact make the volume writable. These permissions are in the volume's Properties | Permissions, where they logically should be. I even made sure that I had the proper "Group" permissions to write to the volume! Apparently changing these permissions and ensuring the proper group membership does nothing, which "violates" a Unix principle. Why on earth is there a separate section, "Actions," where this is done? So is Knoppix Unix, or an attempt to copy Windows, using Windows' non-intuitive and confusing interface? Oh, for the ability to use "grep" in Windows! *RANT MODE OFF*

Again, thanks for the help.