LogMeIn is the Remote Desktop Sharing Tool. If two persons are using LogMeIn in their Computers, they are able to share their Desktops. You can operate others remote desktop, access others files, drives vice versa. It is free for non commercial use.
It uses great encryption algorithm to provide wonderful security against threats. No need to modify Firewall, Router configuration to use this application.
Please click here to download it : https://secure.logmein.com/products/hamachi/vpn.asp?lang=en