You're going to need a fairly advanced rig in order to play Call of Duty: Ghosts on PC, at least if Nvidia are to be believed. You can glance at the minimum requirements for the game over at Geforce.com, and perhaps the most noteworthy thing is that you'll need 6 GB RAM in order to run the game.
Add to that 50 GB harddrive space and a DirectX 11 capable GPU. The CPU demands are more modest as you can make do with a Core 2 Duo or Phenom X3, set ups that are more than 5 years old. As far as recommended specs go Nvidia recommend one of their high-end cards - GeForce GTX 780.
These aren't officially confirmed specifications by Activision, but on the other hand it's unlikely that these have been taken out of thin air by Nvidia.