My motherboard is a Ga-z77x-d3h and I have been intalling drivers. I know which ones I need and don't need, but am having a little trouble understanding the Intel Vga driver. Is this driver something I should install if I already have a discrete graphics card? Or should I install regardless?
The Intel VGA driver is required only for the on-board (integrated) Intel graphics adapter. If you don't ever intend to use the on-board graphics adapter, you don't need that driver.
You can install it if you want to, it won't do any harm. but Windows will not load that driver anyway while ever you have the discrete card installed, so there's not much point installing the Intel driver.
Download the driver while it's available to download and save it just in case you need to use the on-board graphics adapter some day.