Is this good enough for battlefield 3?

Solution
No, it is not. You need to get a better GPU to play the campaing. If you are looking to play multiplayer you will need a stronger processor.

Also, adding more ram will help out.

Right now your priorities should be. GPU>Processor>RAM.

Depending of your resolution we can suggest you a right Gprahics cards and a suitable processor.
No, it is not. You need to get a better GPU to play the campaing. If you are looking to play multiplayer you will need a stronger processor.

Also, adding more ram will help out.

Right now your priorities should be. GPU>Processor>RAM.

Depending of your resolution we can suggest you a right Gprahics cards and a suitable processor.
 
Solution
That GPU is useless for gaming, let me tell you that GPU is only usable when your motherboard doesnt have a video output and you need something cheap to attach your monitior, well that HD 5450 is made for. If you want to game at that resolution, look for an HD 6570 GDDR5, or HD 6670, also the GT 630 or GTX 640 will do the job pretty well.