VPN is a virtual private network. Most companies now-a-days use it. It can be used for many reasons. Basically what is does is it connects you to your companies intranet while away from the office. It will allow you to access your exchange server and intranet sites from anywhere with an internet connection. (however some hotels will have the tunnels blocked) It will also allow you to remote desktop into servers and desktops away from the office. What kind of network are you running? If you have an ISA server they work great for VPN. If not you will need to make sure your firewall and ISP support the routes.
"If it's really a supercomputer, how come the bullets don't bounce off when I shoot it ?"