We have a Windows 2008 server that we want to move offsite to the cloud (we're using Rackspace). It has to talk to our Active Directory domain constantly, so we need a stable site-to-site VPN between it and our datacenter. Rackspace doesn't offer a virtual VPN device, and a quick search shows that Cisco-Windows VPN tunnels don't work well, if it all. We do have a Windows 2008 server in our datacenter that the offsite server could connect to.
What is the best way to get these two Windows 2008 servers to connect to each other?