Hi-
Just to jump into this topic, My 19in CRT and 15in LCD both give differernt 'Real world sizes' as I drag the window from one to the other. Change the screen resolution for either and i can get very small to giant size rectangles from the same window. I think the last time that 100% was a real world setting was for a 13in CRT set to 600 by 480 or may be it was 800 by 600. But it really is best to think of all drawings as a scale drawing and 1:1 means that one inch on the printed drawing will be equal to one inch on your tape measure.
As for real line thickness on your screen- it aint't going happen. The screen display is made up of little squares or pixels and each one can be set to a color. But to draw a line the screen will make it one pixel, or two pixels, or three pixels ...... This is what we see on the computer screen. The lines can have no finer resolution than the screens pixel size.
What I have my CADD class students do is make a VW file with the layer at 1:1. draw twenty or so lines, and using the 'set thickness' choice from the attributes pallet, give each line a thickness that is a series of the possible choices.
EX- using the mm setting for the line thickness give the lines a setting of 0.03, 0.06, 0.12, 0.15, 0.18, 0.21 .....after getting to 0.30 change to a larger jump. 0.40, 0.50, 0.60, 0.70.... after all the lines are set to the line weights, copy them and paste farther down the page, now rotate that set of lines. SAVE this print sample.
When viewed on screen the lines will not show a change in thickness until it is large enough to go to the next pixel and the lines set at an angle will have a jagged stair step look to them.
Print the page at a resoultion of 300 dpi from your printer and they look great.
I have the students go one step further and use the text block to write the setting for eack line under that line. They have to get them lined up with the correct line using the align tools. Now they have a visual grib sheet of what different line weights look like on screen and what they will print as.
From this sample page they choose what line weights they want to set the five choices in the attributes pallet to for the type of drawing look they perfer.
I hope this helps
Ivan