He got 4 GB Ram idiot. & GTA 4 does not depends only on RAM.... the game is Quad Core CPU Utilized, if you have a Quad Core CPU, then you should have no worries while playing it.i know whats the problem.
u have only 1gb ram on ur pc .and gta iv need 2gb ram.
i have aslo this problum but i add 1gb ram the total ram is 2gb ang solved the problem