|I believe both XP and Windows 7 do have built in PPTP technology that can be used to create a tunnel. But I've never done it and don't know how.|
However, if I was interested, before asking in a tech help site like this I would do some googling on my own. Strings like "create a VPN with windows XP/7", "Windows XP/7 native VPN software" or "create a VPN using PPTP in XP/7"
google is your friend...
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.