Windows has the built-in ability to function as VPN server, although this option is hidden. This trick works on both Windows 7 and Windows 8. The server uses the point-to-point tunneling protocol (PPTP.)
Source: How to Create a VPN Server on Your Windows Computer Without Installing Any Software
One day this might come in handy though I need to investigate a bit more on PPTP security issues first: might need to go for L2TP/IPsec instead.
Later: indeed, I should follow Don’t use PPTP, and don’t use IPSEC-PSK either (via: CloudCracker blog)
–jeroen





