First thing to do is to see if you have an upgradeable chip – simply run the Intel auto-detect utility and it will let you know if there are later drivers.
You can also manually identify if you have HD Graphics 4000/2500 or Intel 4 Series Express chipset (for notebooks) by right clicking on the desktop (not Metro tiles) and choosing Screen Resolution and Advanced.
If you qualify go here and download the 125.32MB file (do this off peak). The drivers support 32 and 64 bit.
The update will give you around 10% better graphics performance (in some applications , decrease power draw, give better 3D gaming performance, swat some minor bugs and adds support for OpenCL 1.2. There will be no consequence if you don’t install the latest driver.
Mac users with a Core Processor would update via the Apple Support site.