Slow connection between two offices

I manage a network in two offices, two different cities. They are connected via DSL. One office has windows 2003 server installed and the main has windows 2000 server installed. Occasionally, I have to transfer files between the two offices. It takes upto 4 minutes to copy a single wordperfect document. Are there any setting I can make to speed up the process? (I have installed terminal services and it works fine)