The solution is a little Program, for Windows, called “Dropbox Folder Sync”. You can find it on the following Homepage: http://satyadeepk.in/dropbox-folder-sync/. It’s freeware and only needs an NTFS partition with DropBox installed on it. It works up from Windows XP and only requires .NET framework 4.0.
Once installed, you would be able to Sync/Unsync each folder with an right click on it. “Dropbox Folder Sync” will then copy this folder to your DropBox folder, and create an symbolic link on the same location with the junction utility.