There's a really great free app by Microsoft called SyncToy 2.1 that I think does exactly what you need. Check it out here: Download details: SyncToy 2.1
It was just recently updated and it's really simple and easy to use except it doesn't have a built in scheduler. But there are instructions in the SyncToy help files in the app or on the download page (I can't remember which) on how to schedule it for automatic operation using the Windows Task Scheduler which is part of Windows 7. And . . . there are both 32 and 64 bit versions.
Otherwise, there is a paid app called "Second Copy 7" which does the same thing but has its own built in scheduler.
But I think the free SyncToy app is just what the doctor ordered for you. I use it to synchronize folders between two external drives using a mode it has called "echo" which probably is the mode you would want to use. Another cool thing is that it's really fast. Finally, it also gives you a report (if you're interested) of exactly what it did to which files after the job is completed.