There are so many easy and good commercial solutions under windows as TrueImage Server... but I suppose you are looking for something free.
There is one straightaway solution, this is Clonezilla installed as a server, but unfortunately this must be running under a Linux machine.
http://clonezilla.org/clonezilla-SE/
The other solution is to run Clonezilla as a boot image only. I didn't try yet, I don't know if in the "CD boot" there is a "server mode" able to initiate backup from client machine and repatriate data, or if this CD is only intented for client mode (so in this case each client must boot the clonezilla CD).
The third solution is to "PXE boot" the Clonezilla CD image on a FreeBSD server
http://www.wonkity.com/~wblock/docs/html/pxe.html
If you like "cooking", in fact each Windows workstation has some built-in imaging tools.
But you must not use
imagex, here is the explanation :
https://support.microsoft.com/en-us/kb/935467
Since Windows Vista MS has integrated in Workstation distribution a backup incremental tool in Pro/Ultimate versions working with the VSS service to do live backups. Finally MS has decided to keep this imaging tool in the last Windows 10 (under Win8, MS tried to remove this function)
So it could be possible to set up a scheduled task on each workstation by choosing a FreeBSD server as a remote backup location (Windows has some tools to speak "nfs", or simply set up a samba server on the FreeBSD machine). You could alternatively create a VB/Java script as you could implement all kind of tests to make sure the backup is ok.
For restoration you could build and insert a custom "WINPE" image in the FreeBSD server through PXE network.
The FreeBSD machine run at the same time a samba share holding the backup images. So the client boot on FreeBSD PXE to launch the "WINPE" image. If you have done a good job, your WinPE should integrate necessary tools to access the FreeBSD Samba Share.
Winbuilder is a simple but powerful tool to create customized WInPE Boot environment :
http://winbuilder.net/
This website speaks about different projects of "recovery environment" developed with WinBuilder. You can get inspiration here. WinBuilder syntax is not complicated, you can learn this very quickly by analysing existing scripts.
http://reboot.pro/forum/22-winbuilder/
The Win7PESE is most likely the most mature project that you can integrate onto a CD/DVD, an USB key or even a classical "hard drive layout" so with no wim CD image at all. In fact the official Windows CD installation has already built-in recovery tool, but the main problem will be to access the network. For this reason you may need a more advanced CD/DVD image like WIN7PESE
http://w7pese.cwcodes.net/
NOTE FOR THE MODERATOR : legality of WinBuilder and affiliated projects as Win7PE SE has been discussed some years ago. Legal department of Microsoft tried to close theses projects, but the explanations given at this time by the different teams have convinced the legal department of Redmond that there was no legal issue... so Microsoft is perfectly aware, and projects are still alive since many years now.
