I would suggest using dropbox, this will mean they sync whenever they are connected to any internet connection. It also has a lan sync feature that syncs all the dropbox folders over your local network.
You can also use the web application to access and upload files.
I rely on this everyday and I couldn't even imagine living without it.
For example I will just change a file thats in the my dropbox folder to update my webserver but I can do this from any pc without the use of any ssh or telenet commands.
EDIT: For not using the internet you can always just share the files from both pc over your network that you have currently been copying and pasting into... write a batch script that maps the other computers local drive you would like you update with the most current files and xcopy them to that drive... you can then write another batch script that will map that drive and download said folder to the pc you are on. Its sketchy but it could work. You would need to be careful on which one you run. It would work if you edit a bunch of files and then want a quick way to upload those files to the other computer without copy and pasting. Say the computer wasnt on the network when you edited the files you just run the script that copys the files from the other computer. Sorry if this is confusing.