xBlaz3kx :
Probably will lag depending even on your RAM frequency and capacity. OC your CPU and replace the RAM and you should be good.
I disagree completely with the Ram statement. Ram matters very little when it comes to gaming. (As long as you have 8gigs)
Overclocking a cpu will help, but considering I don't know of a quad core pentium chip it won't help play games that want 4 cores. Lots of new games don't play well on dual cores.
So basically, yes a graphics card will help a lot in games that are ok running on dual cores. No, it won't help you run games that want quad cores. Either way I would upgrade the graphics card before the cpu.