You can find Intel drivers here.

Navigate to the "Graphics" menu on the left hand side of the page.

Select your type of computer (Desktop/Laptop) and then select your graphics card as specified in the DirectX Diagnostics Tool from the the list.

Select your operating system and click continue. As said before, the number of bits the OS has can be found by right clicking on "Computer" on the desktop and selecting properties. Under the "System" section labelled "System type:" you should find the number.

Good luck