Video options for battlefield 3 (bad computer) [closed]

My computer is pretty old and not so fit for playing bf3 but I wonder which video options I should use to get it to look as good as possible without being laggy.

My specs:
AMD Phenom X3 2.10 GHz
3 GB RAM
Nvidia Gforce 9600 GS

I have a 24" screen and would prefer the game to fit in without having a black frame but it's not as important as getting it to look as good as possible without lag.

I've been playing on low with about 1200x700 resolution (don't remember the exact numbers), but is there any more suited option?

So you have the main "Graphics Quality" setting set to "Low" in this menu? (instead of ultra)

If not, do that. Then set the "Fullscreen Resolution" to whatever resolution Windows is using. If you have a 24" monitor, probably 1920x1200. Also be sure you turn the motion blur all the way down and disable Vertical Sync.