Well you have a few things in you need to think about.

Moving netboot services to the FOG server. This is pretty easy enough to do. You change the dhcp options 66 and 67 to point to your FOG server from your current netboot server. I do have a tutorial on how to setup FOG as a netboot server here: https://forums.fogproject.org/topic/10944/using-fog-to-pxe-boot-into-your-favorite-installer-images This system uses FOG to create the custom iPXE menu entries to boot into your linix distro’s live installer environment. You may have to tweak the kernel parameters to load your installer seed file. The nfs disk structure and preseed file organization is up to you since netbooting is not a supported feature of FOG, but a hack using the FOG infrastructure for netbooting.

Once you have your netboot installer for linux configured then you can focus on the windows bits.