How can I connect to my friend... and do what [I want] to do [to him] from my house?
Yes, you can use real vnc with any windows OS, even 95.
What about computers on the same network? Will it work and what info would I need?
Install RealVNC client and server on both PCs. Connect to the LAN IP of whatever PC you want to control. No need to specify a port, or do any other work.
VNC does not use VPN passthrough.
Finally downloaded RealVNC and got it working following Thrax's instructions. However, I'm using UltraVNC, like Leo, as it allows File Transfer which is useful.
Thanks guys and Sniper for the thread.