How can I track my files in the pc that have been copied to an external harddisk? Or vice versa?

Answer 1

There are programs specifically for tracking when files get copied (usually for large servers to keep people from accidentally overwriting each others files).

Your best bet is to just make a log, and mark whenever you copy something.

Answer 2

Do you mean you want to check your hard drive against the external to see if they match?

This is a painstaking job. Frankly, I would find it easier to do a complete backup.

Open My Documents
Open the external hard drive
right-click on a blank spot on the taskbar and choose "tile vertically

select a folder on c:
copy
click on the external hard drive
paste

when finished, right-click the taskbar and choose "undo tile."

Answer 3

You would need a 3rd. party application that does document checkin/checkout or file monitoring.