Dropbox for Business users can have both a personal and work Dropbox account on iPhone or iPad. Use version 3.1 or higher of the Dropbox app. to use both your personal and work Dropbox on your iPhone.
If you are installing the 'Dropbox Desktop Application' for the first time on Windows XP, then you will need to sign in to both Dropbox accounts.
If you are an existing Dropbox user, you will need to sign in to your second Dropbox account.