I did exactly this today to test the process and got up to 3.5gb of dropbox storage today
Why not use copy.com instead, or Google drive for that matter? Copy.com gives you 15gb, and a download folder etc as well. Here is a ref link https://copy.com?r=ezGlAW for an extra 5gb (gives me an extra 5gb as well - feel free to just go to the site I dont need the space). I prefer the interface over Gdrive