How do I synchronise two folders in real-time in Windows 7?

Problem

I want to synchronise two folders in real time under Windows 7. Basically, I want to monitor a folder and synchronise each change (new files, changed files, deleted files) to another drive. It has to be in real time, so it gets synchronised instantly when a change happens. A one-direction synchronisation is enough. I tried Microsoft's SyncToy, but it does only syncing by hand or scheduled (thus not satisfying the "real-time" requirement). Can this be achieved with Windows 7 itself? If not, are there other methods of doing this?