Offsite Windows DC Active Directory

Hi to everyone,
I have currently got a Win2K domain with 2 Domain Controllers, what I want to do is; as part of my DR plan.
I want to have an additional Domain Controller which is kept offsite and connects through a VPN to my main DC. The VPN Connection will be established between 2 Netgear FVL328 routers and hopefully a static IP address on each end.
My question, will this setup work, and What will happen if the VPN goes down, will it be secure enough?

Thanks for your help in advance.
Michael