I am assuming you are wondering if having this card would bring your cpu's performance down??....well that is true but only in applications where your cpu and gpu work in tandem, like in games or heavy rendering.
In rendering the output would be more time required to finish the render. In games, less frames/second (but if it's above 30 frame/sec you wont notice any difference) also some games will not allow you to max out certain in-game settings which are controlled by the gpu.
In everything else, you'll be having no problems at all. Internet's gonna run fine, files will transfer at blazing speeds and applications will install and run as they are supposed to...quick!!
I hope this answers some questions
good luck
-satyam