Maybe on medium, not on high - well maybe a mixture of both. You can juggle the settings a bit so that the things you care about more are done better than less significant things, such as night shadows and water textures. Your onboard lame Geforce 6150 is irrelevant because it would most likely have been automatically disabled when you plugged a proper card into the motherboard, that's only for if you have no graphics card.
Edit: Your PCIe x16 slot will take any PCI Express card, you must make sure that the power supply can handle your choice of card though and replace it if not. The HD6670 is a decent mid range card though. The only other limiting factor is your budget, and I have no idea how much money 6000k represents.
Gta IV is a particularly bad pc port, the pc version of that game is ridiculously cpu heavy and still has fps issues on higher end machines. I get similar fps with an extreme modded version of the game as I do with the original lol. Gtx 550 ti / 560 ti would be worth the extra money but honestly I don't think your cpu is going to cope with it : (. Sorry.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.