I second the usefulness of Robocopy. I've been using it for years (debuted in some resource kit (Win2k?) and then someone wrote a GUI for it for you sissies: http://technet.microsoft.com/en-us/magazine/cc160891.aspx

Create a .bat file that calls other more granular bat files (so that you can backup certain things more frequently) and then schedule a task to run nightly.