So I currently have a setup which has two monitors. Recently I have been thinking that this setup is less than ideal, because there is no primary monitor right in front of me for me to focus on, I end up choosing one of them arbitrarily (the right one seems to win most of the time) and then I get some pain from looking to one side most of the day. So, I want to get a third monitor. The problem is: I can't buy a third monitor which is the same dimensions as the two I have, because everything is widescreen nowadays.
The monitors I have right now are a pair of Dell 2001FPs. This gives me a great resolution of 1600x1200, and I want to have optimally 1200 resolution in the vertical, so that it will match. I'm fine with the new one being widescreen - in fact it makes sense to have a primary as widescreen to me and off to the sides have 4:3s. The problem is that none of the specs online will tell me how tall the viewable area is. I've found a number of monitors with 1920x1200 resolution, but I don't know which size (diagonal) to get.
How can I find out how tall physically a monitor will be so it matches with the ones I have?