Try OpenVPN (http://openvpn.net/). It's cross-platform, completely free, extremely secure, and once configured it's extremely easy to deploy. I can't confirm whether it specifically targets x64, but the x86 build should work on the x64 architecture.
Edit: I should mention that OpenVPN won a "Bossie" in 2007 as the best Open Source VPN.
Also, OpenVPN 2.1 is Vista-ready on both x86 and x64.
You could use Windows 2008 Server and the built-in Secure Socket Tunneling Protocol? You could use the built-in Windows Vista/7 networking client and the configuration is very simple.
Try OpenVPN (http://openvpn.net/). It's cross-platform, completely free, extremely secure, and once configured it's extremely easy to deploy. I can't confirm whether it specifically targets x64, but the x86 build should work on the x64 architecture.
Edit: I should mention that OpenVPN won a "Bossie" in 2007 as the best Open Source VPN.
Also, OpenVPN 2.1 is Vista-ready on both x86 and x64.
You could use Windows 2008 Server and the built-in Secure Socket Tunneling Protocol? You could use the built-in Windows Vista/7 networking client and the configuration is very simple.