A 4GB 760 costs the same as 770 and it's a no contest: 770 wins easily. The only cards that can use 4gb are 290, 290x, and Titan. Any other cards with 4 gb of vram just can't keep decent frames running all 4 gb since it's usually max detail and 8x MSAA. The 280x is to expensive in US, but might be different for you . Gtx 770 and 280x almost have same preformance with 280x having 5 percent preformance lead. With 770/280x, pretty much all games with be maxed at 1080p and both black ops games will be maxed at about 80% load. Lastly, your processor is still very powerful so you will have no problem gaming with it for now.