I have no issues running dual monitors with my integrated Intel HD 2500 graphics.
I tested a Nvidia GeForce GT 710 PCIe GPU and found no noticeable performance improvement over the Intel HD. I would say use the money for something else.
Intel has really improved their graphics since the old days. IMO, the built-in stuff is now as good as the entry-level discrete GPUs.
You really only need to add a GPU if you select a motherboard or CPU without graphics support. Or if you want to play 3D games on your DAW.