Information about VPN

[Jean Sagi]

I admit it: I haven't read much about what I'm going to ask.

(I'm actually on http://computer.howstuffworks.com/vpn.htm), so:

How does a VPN work?

I know nothing about it, so it would be much appreciated if you are so 
kind in pointing me to good resources on this subject.

I would like to know for example how can I access the network the 
company I work for from Linux (obviously) and from Windows XP (Yeah... 
the evil always).

Your suggestions will be very much appreciated.


J.