Update: Victoria Bampton has suggested in the comments that you could setup a symbolic link between this folder and dropbox, for automatic backup. I’ve covered these links in the past in relation to moving the Previews folder. While this was a Mac post, there are Win related links in the comments of the post.

Update 2: Again from the comments: http://lifehacker.com/5154698/sync-files-and-folders-outside-your-my-dropbox-folder