NO IT IS NOT.
Driver cleaner pro is from 2005 and would corrupt your OS if you use it without previously uninstalling the drivers.
You can buy the NEW version of driver cleaner pro, but it now has a new name.
Or you can use driver sweeper.
All of it is unnecessary though... simple straight forward solution:
1. Uninstall the ATI driver from add/remove programs
2. Turn off your computer
3. Swap cards.
4. Install the nvidia drivers.
5. Restart computer
6. If driver issues are experienced install the nvidia drivers AGAIN over the previous ones WITHOUT uninstalling existing drivers. (only uninstall when swapping cards)
7. If driver issues continue uninstall all drivers, boot to safe mode, run driver sweeper, restart, and reinstall nvidia drivers.
If you were to go the other way around (nvidia to ATI) the process is the same, only swap the names nvidia and ATI in the list.