|"dedicated memory of 32 mb|
but i have 1664 avaliable memory"
Dedicated is the amount that matters, the other is the shared amount which varies based on need.
Here are the graphics requirements for GTA IV:
Video Card (minimum): 256MB NVidia 7900 / 256MB ATI X1900
Video Card (recommended): 512MB NVIDIA 8600 / 512MB ATI 3870
You need to meet both the memory AND the GPU requirements, your system meets can upgrade to a gaming graphics card. If you have a laptop, there's nothing you can do because the graphics are built-in to either the motherboard or the APU.
If you want to be sure, try this: http://systemrequirementslab.com/cyri
The following article will help you to choose a decent graphics card. Make sure to stay within what your power supply can handle or it will need to be upgraded as well: