PureSync by Jumping Bytes is a Windows program to synchronize files and folders, and to do backups e.g. automatically in the background.

Highlights:
Side by side compare view
Automatic synchronization and backups
NAS and FTP support
Easy to use but still many options
Change log (16.12.2010):
New features:
Automatic sync/backups:
- automatic starting of a job after computer has not been used for x seconds or minutes
- delayed starting ob jobs in case CPU usage is above x %.
New explorer context menu: the options depends now on the selected items (file(s), folder(s), drive(s))
Windows 7: the progress is now shown in the taskbar
Changed drive letter: PureSync now checks if the drive letter hsa been changed and will now ask whether to use the new drive letter or not.
Improved comparing all files regardless of their locations
FTP: now connections with port are working (e.g. //192.178.1.1:21)
Foto Sync with destination with the date of the file(s), now works with source folders with *
Fixed bugs:
Fixed problem with files with the same name as the folder they are in
Fixed an endless loop
Global settings 'max. number of automatic ...' did not work properly
Setup Wizard: fixed bug editing the file types
Size in the status bar was sometimes wrong
Fixed bug synchronising when a ? was in a folder spec
PureSync Personal is free for personal use
OS: Windows 98, ME, 2000, XP, Vista, 7, Server 2003, 2003 R2, 2008, 2008 R2 (including x64 versions)

More info: PureSync (WOT: Green)
Download: PureSync 2.8.0