Scripting help needed

I have a situation on a brand new network (Win2K server, WinXP Pro workstations) where they are (unfortunately) still using a number of DOS programs. They need to be able to print from these programs, obviously, so I need to capture a printer port to a specific printer for each user. The problem: I need a method of capturing the printer port to that user's default printer as he or she logs on. IOW, I don't want to have to go to each workstation individually and create a persistent port mapping. I want to be able to do it from a login script. My only problem is that I don't know how to identify the user's default Windows printer - does anyone know of some variable or scripting whiz-bang that I can use that will be able to find this information as the user logs on?