I have a Cisco 871 Router at my home, running C870-advipservicesk9 11.T2.
I have never set up a VPN on it.
I have a static WAN address from my ISP.
My goal (and I don't know if this is even possible using this router) is to be able to connect to this router (which sits at my house) from my laptop running Windows XP, when I'm at coffee shops, using a VPN connection, such that my internet traffic goes from my laptop at the coffee shop, to the router (via VPN), and from my router out to the internet... the idea being to establish a secure connection at the coffee shop end, so that my traffic can't be sniffed by others in the coffee shop.
That is, my router at home would be a "middleman" between myself at the coffee shop and the internet.
Ideally, I'd like to do this without adding any software on the XP machine, using XP's built in VPN capability, though I don't know if that's compatible with any of the VPN setups that the Cisco offers. (It seems to have quite a few, and I'm not sure which if any of them are right for this scenario -- it seems to have things called "Site-to-Site VPN," "Easy VPN Remote," "Easy VPN Server," "Dynamic Multipoint VPN," "SSL VPN," etc.)
Can someone provide a step-by-step telling me how to set this up, both on the router and on the XP machine?