Get Ready to Download, Activate and Play GTA IV !
>First download and Install GTA IV – Download Link
>Now Download and Apply the Official Single Player Patch (Patch v. 1.0.4.0) – Do not use the latest >1.0.7.0 patch it only upgrades Multi player functions – Download Link
>Now you can Uninstall ‘Rockstar Games Social Club’.Go to Control Panel and Uninstall it
>After that Download and Install “Games for Windows Marketplace” - Download Link
Note: (((Follow the steps given below correctly  in order to activate your GTA IV copy)))

How to Activate GTA IV?
Download On HAX GTA IV Activator and Graphic Fixer
Extract zip file and Run On HAX GTA IV Activator and Graphic Fixer.exe
Browser and select the home folder of your GTA IV installation
Click on “Activate & Fix” button
A Progress bar will fill and the activator will quit by itself
Now GTA IV is fully activated

How to Fix Graphics in GTA IV:
You have already activated your game,let’s fix graphics now
Launch GTA IV from your desktop shortcut (or go to GTA IV home folder and run Launch GTA IV)
Wait till Game loads and Go to Options menu
Select Graphics Tab
Now you can change game screen resolution as you want (by default GTA IV will not let you to change this)
Set it to a lower value you prefer
Change rendering options and other options to “Low” if you have a low GPU (VGA memory)
Now Apply by Pressing Space and Press enter again if it gives any messages
Close GTA IV from Quit Menu and restart the Game
Now you are ready to PLAY