Can I backup all computers in my network to my server using free software or windows only? [closed]

I have lots of different computers with windows (XP, 2003, vista, 7) and I am trying to backup some folders from each computer in the network to server. I want folders to synchronise every few hours!

Is that possible using only windows?
If I need a program, which one?

You can create a schedule task and use MS's synctoy via commandline to do this, you can also use robocopy which is built into windows and replaced xcopy.

Update

I would wrap my robocopy commands in a powershell script if you want to customize folders and destinations that depend on several factors.

Update 2

Here is the synctoycmd.exe help:

C:\Program Files\SyncToy 2.1>SyncToyCmd.exe /?
Usage:     SyncToyCmd [-args]
   -R           Run all folder pairs that are marked as Active for Run All.
   -R <name>    Run the named folder pair (only one folder pair can be specified
).
   -?           Display this help.

Examples:
   SyncToyCmd -R MyFolderPair
   SyncToyCmd -R

C:\Program Files\SyncToy 2.1>

For the program you want to specify the full path to synctoycmd, and specify your arguments accordingly. It's best to create a folder pair using the gui first, in fact you have to for this to work.

If you want to use only Windows-included tools, you can set up the copy job using batch files, powershell scripts, VB scripts, etc and then fire it off at a specified interval using the Task Scheduler.

If you want a more wizard-like experience (no coding/scripting required), there are tons of free and paid synchronization programs out on the web. A couple that I have used include Pure Sync and Allway Sync (I still use Pure Sync regularly). Many of the paid programs have "free for personal use" options (both of my suggested programs do this).