VPN stands for Virtual Private Network. It is used to connect to a network via the Internet. The difference with VPN as apposed to just connecting directly to the network is security. VPN creates a secure connection to a network. This secure connection makes if very difficult for a hacker to intercept that network traffic you are sending back and forth.
VPN will allow you to connect to the RIT network from home. You will be able to access your H:\ and P:\ drives just as you would sitting in your office. Also, you would be able to connect to printers that are on the network to print to them from home. You can connect to RIT using the VPN over just about any Internet Service. This will work over RoadRunner, Frontier Lighting Link, AOL Dialup, or even from a hotel while you are traveling.
There is more information available on ITS's web site at http://www.rit.edu/its/services/vpn/.