Cyker: We use openvpn but i must admit it's a bigger pita to get working than hamachi.
For those of you that don't know, Hamachi is a sort of peer-to-peer VPN, designed less for security but more as a LAN emulator for e.g. LAN-only multiplayer stuff.
Was a nifty bit of software, very very easy to use and ui friendly before it got bought out.
OpenVPN is a client-server VPN and it's more of a pain to set up, esp. since someone has to be the server and it needs to be tuned for lower latency, but it works okay and we even used to tunnel IPX across it before we started using DOSBOX for that!