Uninstalling and re-installing is cleanest. Upgrades sometimes work, if the new version properly recognizes and uninstalls all pieces of the prior one. Since you've got an OEM PC however, it is possible the prior drivers contained customizations not accounted-for by the new card's driver installation. You could wait for instability (which may or may not occur), or just take 10-20 minutes or so and wipe out all prior nVidia / video drivers and re-install.
It doesn't take long just put into google "Nvidia drivers" and it will take you to the driver page all you do from there is select your model and operating system and it will download. From there just open the downloaded file and go though it.
I have this same question.
I have the 320.49 driver for NVIDIA currently.
I would be downloading the latest 332.21 driver.
If I want to upgrade to a new GPU(650) from my 210 then do I need to still uninstall the driver(it supports both cards)?