core 2 duo was good for gaming 5 years ago when the main resolution was 1024x768 and everyone was playing counter strike 1.6, if buying today, its completely and utterly obsolete, I would've gone for atleast a 3rd gen i3, pretty cheap and a 1000x better than core 2 duo's, probably it has DDR2 ram, which is also obsolete as we're already getting into DDR4, cooling on dell mainstream cases is crap.
If you're getting a new gpu, I would usually suggest to get the most expensive one you can afford, in this world, usually more expensive = better, but in your case it would be useless to go beyond a 750ti at the maximum.
and NO, by todays standards, the pc you just bought is not good, sorry to break it to you.