Newby ? - mega2560 and Ethernet shield to read (3) 1-5v inputs into desktop app

I have 3 pressure sensors (outputting 1-5v) on 2 filter units (for dp readings)

And "dp" means what ?

5v correlates to 20ma, which is 100 psig.

That's 10.23 analog counts per psig.
What is the nominal operating pressure for the "dp" (whatever that is) ?

My goal would be a simple window I can pull up and view dp1 and dp2 where dp1=p2-p1 and dp2=p3-p2.

I don't see any mention of a windows application to do this. How does this relate to arduinos ? Are you asking us to recommend a windows application to view or is the "simple window" you refer to the Serial Monitor ?(that is a "simple window, if that is the
criteria you are specifying)