This would depend a bit, Sanal.
One part of thinking about your RAM is the actual amount (too low, and FSX slows down a bit), the other one would be the speed (has some influence, but not that much).
So what's your overall amount of RAM? Did you post the data of one module there (I assume) or are those 2048MB all there is so far?

Maybe you can post some more of your system details since RAM plays a role in FSX performance, but not the biggest one. If you're not so happy with your current performance, maybe one can put some light on the weak spot of your system if he knows about it.

We have to be aware that this isn't a 707 question though.  :P