Mirroring Win2k Shares over a WAN

I want to be able to mirror some of the shares on 3 servers to shares on a NAS box over a WAN. It’ll be about 10GB but has to run over night on a Saturday as that’s the only time the network is quiet enough.

Is there any software that I can use to do it? I’ve looked at things like xcopy, but only want to do incremental copies – only files that have changed. Googling has produced nothing usefull. I’m happy to use VBS but have very limited knowledge and even less experience with it.

Thanks

Matt