Yeh, good luck. I think if you have had it demoed, it's probably passed the test anyway and you have ordered but fwiw:

I think a lot of the pixel resolution vs screen dimensions comes down to our own eysights and what we are comfortable with. My monitor will do a lot more than 1024 x 768 but things start getting too small for me much above that. In fact when my 17" monitor blew, I went to a 19" to feel that bit more comfortable using the same resolution rather than to enable me to use higher resolutions and fit more stuff on the page.

I suppose a way to look at the question you asked before would be to try to work out the number of pixels there would be per inch of screen. I'm assuming all monitor measurements are the diagonal, that you see the whole screen (viewable area is a bit smaller) and have used the figures you gave me.

On a 19" at 4:3 we have a screen of 15.2 x 11.4. At 1024 x 768, that gives (horizontal and vertical) 67.37 pixels per inch.

On a 30" at 5:3 (I think a lot of wide screens are 16:9 btw) we have a screen of 26.2 x 14.7. At 1280 x 768, that gives (h & v) 49.76 pixels per inch.