I run a tax office that has two computers running to a central file server and I want to have an offsite backup in case the building burns down or the hard drives go out. All the work files from both computers sync to the server directly so the programs we use (tax agent 2012) and a few others sync automatically with the server. I need a backup solution, storage space is not a huge problem as the files are not that large, but I don't want to be bottle-necked by a storage limit. I'm currently running two machines that use windows XP professional and the server runs Windows Server 2003.
What would be my best options to back up the server, and the two computers for total protection?