Sony VAIO, might be having ATI graphics, possibly HD5450 series.
The game, GTA IV is very demanding game, in terms of system.
Even I cant run it on full graphics on my system, though its a desktop.
I ran it on 1920 X 1080, more than medium details.
If i tweak the settings to high, it starts lagging.
So dont try to increase the settings, try to play it on minimum settings.
Because you cant upgrade anything on a laptop that easily.