Do you have still like to use different hard drives on your system to keep your data separate? If so, then perhaps Profile Relocator by Joseph Cox will be useful for you.
Profile Relocator is a step-based application that allows the re-locating of the Windows Users profile directory. Once re-located, any created profiles will appear in the new location in their entirety. The advantage to doing this allows profiles to be stored in a location that doesn’t reside on the system drive, ensuring that profile data isn’t compromised as a result of re-installation or system failure.
Profile Relocator has been designed to work with Windows XP, Vista, and 7.
Please note that this application should ideally be used on new installations of Windows; PR should be used, and then the final profile should be created. See the included documentation for step-by-step information. PR will not move existing profiles as this can be dangerous