Video card will not help your rebuild times. SolidWorks is CPU bound. You are severely limited in CPU performance with the G2120 cpu. This is an extremely low end cpu. Good for email and web surfing at best?
Rendering on that system will be painful. PV360 rendering is all cpu. A video card will not help rendering performance.
How much did you spend for this system? What are the rest of the specs? Make and model of system? What are the specs of your laptop? CPU in particular?
I am worried that you purchased a desktop with less horspepower then your laptop. Hard to know without knowing your laptop specs.
Save your money as the video card will not help your SolidWorks performance.