[cysus]

I would suggest Hamachi, once installed it appears as a network adapter. Simply create a private Hamachi network, log in to that on all the systems you want on the network and it will act just as though you're physically connected (except for the internet speed limitation). It's the best VPN software I've come across, the only downside I can see is the created network is managed by Hamachi's server (if their server went down you wouldn't be able to reconnect to your network) rather than being completely independant.
http://www.hamachi.cc/
It has all the proper encryption, etc and it's a very simple UI, not that you really ever need to use it for anything other than logging in(I use it for it's chat function). Anyway, I've never had any problems or downtime with Hamachi, no complaints.