You don't want to install the CD one since it'll be out dated efore the consumer receives it. It's offered for emergencies such as the PC not detecting it. But installing it does no hamr, as for updating, you can kee the old driver. The ultimate way, usually used whn having issues or downgrading, is to uninstall and then install the new-but not at all necessary.
But go for their new beta drivers from their website, they fixed a number of problems
(From what I'm told, fellow Nvidia owner currently-had AMD/ATI)
I'll update with a link;
Edit: AMD Beta Drivers