Windows 2003 backup batch file

I have a specific folder C:\munex on a win2003 server that I need backed up everyday to a external hard drive in a enclosure that is connected via a usb port, there are 2 drives involved and they are alternated on a daily basis, how do I write a batch file to let this folder backup at a specific time everyday to the external harddrive. Will this backup be a full backup everyday or will it do an incremental backup?