VNC is available in several different versions, but all do much the same thing.? I use UltraVNC occasionally and it works very well.? However, to connect to the remote server, you need to know the IP address of the remote computer.? If it's on a static IP address, then it's easy enough to do, but if it's on dialup or DSL where the IP address changes from time to time, then it becomes a bit more difficult.? Take a look at dyndns.org one of the similar services that will associate the IP address with a name so you don't have to keep changing the IP address in the client program every time you want to connect.
Also, check out the Windows XP Remote Desktop feature if you have XP Pro.