I was looking for something like rsync that I can use on Windows. I know that I could install many of the Linux utilities on Windows but I just wanted to see if there was something built-in. Well...robocopy!
robocopy source_dir z:\backup\dest_dir /MIR
The /MIR mirrors the entire directory tree. I'm tempted to say that I actually like it just as much as, or maybe more than, rsync.