Man, I don't play MTA with whole graphics, EVER. I'm fine with 256 MB.
In fact, I prefer 800x600 than 1280x768 by some reason.
Call me freak, but I still prefer it.
My video settings:
-800x600x16
-Medium Graphics.
-Draw Dist. 100%
-No volumetric shadows or grass effect.
-No filter.
-No antialiasing.
-Brightness 100% (windowed mode becomes darker )
With that, I can run MTA good unless the map is very much decorated (Vortex, for example).