Oh I didn't see that, the picture threw me off.  I thought you had 2GB. :doh:   
Like cichlidfan said, Try out DCS: World and see how at least the game world runs.  It has an Su-25T that you can fly around.   http://www.digitalcombatsimulator.com/index.php?ProductId=21&end_pos=137&scr=product&lang=en   
This game mostly taxes the CPU, the graphics engine is much more efficient than anything Microsoft could come up with for FSX.