I would like to back up data on my laptop (word files, photos, music etc...essentiallty the my documents folder). I was thinking of getting an external hard drive and copying the contents of the 'my doc' folder. However each time I add a new photo or new doc to the 'my doc folder'; I will need to identify and update the backup folder on the external hard drive which is quite tedious.

Ideally I would like the computer to understand whats new in the 'my doc' folder and update just those bits on the back up folder in the external hard drive.

Can someone please suggest a good and non tedious back up starategy using an external hard drive?

Thanks