It has been known that some people cant run because they have "too good" of a computer. My friend cant run it, and has great specs, but cant run it. You would actually have to down grade to play the game.
Yeah...........no. Not even a little bit, unless you mean too new of an OS that won't support Windows 95 games or something.
GTA IV was a poorly optimized console port and needs a quad core CPU to perform well. I suspect your dual core CPU is holding you back. You will also need at least 4GB of RAM. No game from the last 5 - 7 years is going to run with 2GB.