Nas off site backups

hi,

In our small office, i am the default IT department. please excuse my lack of knowledge of the technical issues, i hope someone can help!

We currently have a NAS solution to backup of our work (ReadyNas Duo), but i would like to implement an additional off-site backup.

There is an option to backup the NAS via a USB to a saparate hard drive (fair enough), but that would involve remembering to bring the drive in, backing up, and remembering to take it away again every couple days, and i am very busy as IT is not my job!

Is there a way to use the existing remote access arrangements (ftp, https, cifs) and some automated software on a remote computer (ie my pc at home), to backup all the files that have changed since the last backup each time the remote computer is connected to the internet?

i know that there are companies which offer remote online off site backups, but if i can do it myself for little cost, i would prefer it.

thanks for any suggestions. )