I have been using Dropbox for years but on several occasions I've had to reinstall and then fight with dropbox to use the folder that is already there instead of insisting on re-downloading terabytes of data. How hard could it be to have a step in the install that asks if you want to re-link to an existing folder? Or use the previous settings from my account? I always keep dropbox on my second, much larger drive, not on the default drive C:.