The following backup tools are all freeware, and as such can be downloaded and used for free. Note that some have premium versions, so when following the links, be careful to choose the correct version of the software.
Karen’s Replicator

click to enlarge
Recently updated to v3.6.8, Karen’s Replicator is a very useful backup management utility that allows you to schedule backups of files, folders and entire drives to destinations anywhere on your network.
Having been around since 2002, Karen’s Replicator is one of the most feature pack backup freeware tools – you can choose to backup only files that have changed, schedule days when backups should not be taken as well as skip certain files.
Visit www.karenware.com to download Karen’s Replicator v3.6.8 – at just 2MB, it is a great solution!
EaseUS

click to enlarge
Todo Backup 1.1 from EaseUS is designed for use with each version of Microsofts operating system from Windows 2000 to Windows 7 and is particularly good at backing up the system partition to get your PC back up and running again following a severe crash or disk failure.
This freeware backup utility can also be used to clone disks as well as mount backups as virtual drives to be browsed, as well as offering compression of new backups.
Complete with standard backup functions, Todo Backup is also a great choice for backing up the operating system and applications from one hard disk to another in order replace an older or smaller disk drive.
EaseUS Todo Backup 1.1 can be downloaded free via www.todo-backup.com.