Hamachi
http://www.hamachi.cc/

With Hamachi you can organize two or more computers with an Internet connection into their own virtual network for direct secure communication.

Hamachi is fast, secure and simple. It is also free.

Think - LAN over the Internet.

Think - Zero-configuration VPN.

Think - Secure peer-to-peer.

Access computers remotely. Use Windows File Sharing. Play LAN games. Run private Web or FTP servers. Communicate directly. Stay connected.



HOW-TO: Set up your network (Win XP)

Download Hamachi.

Now that you have Hamachi install it, and either create or join an existing network.

You will now see a list of users, by default you will just see the VPN assigned IP address. Right click on the users IP and select 'Set Label' --> 'Nickname'. You will now be able to read the persons nick and know who they are.

If the users names are greyed out - that means that at the moment they are not online.

Now, if you go to 'my network places' and 'view workgroup computers' you should be able to see the computer of anyone who is currently online. If you click on the computer icon you'll also be able to see any folders they've elected to share with you.

Make sure that someone else is online. If you can't see any computers on your workgroup you either have a network problem or they are all currently offline.

Make sure that you have the windows firewall turned off on the Hamachi device that you can see in 'network connections' it will just cause problems.

Troubleshooting

If you are not already on a network, you may need to run the network setup wizard.

'Setup a home or small office network' --> 'Next' --> 'Next' --> 'Tick Ignore disconnected Hardware' --> 'Next' --> 'Tick Other' --> 'Next' --> 'Tick This computer belongs to a network that does not have an internet connection' --> 'Next' --> From now on keep on going 'next' and select the Hamachi virtual adapter as your network connection.

Check any other software/hardware firewall you may have.

Check that any firewalls that you may have on your computer are not trying to block connections.

Make sure that the other users you are trying to see are using the same network name.