The specs say that PC has "NVIDIA GeForce GTX 650 1GB " Thats a stand alone video card, and has display outputs that would be in addition to the VGA port that comes from the MB. The modern GTX 650 (kepler based) will support all sorts of video outs, not just VGA. When you install the PC use the port off the video card, not the VGA on the back that comes from the MB.
You will be using DVI or HDMI to connect your monitor to the PC tower, not VGA. That will give you clearer text characters (google Microsoft cleartype).
Go for any 20" LCD that has a ton of good reviews that is cheap on black friday (day after thanksgiving) prices will be rock bottom then. Also consider a slightly larger 24", prices have really dropped.