Portrait Landscape Help

[jadawgis732]

I'm doing a dual or tri monitor setup with a 25.5 or 27 1920x1200 in the middle flanked by 17" 1280x1024 or 1440x900 (with 25.5, 27 respectively), but this is depending on whether or not the displays must match up in a pixel perfect manner meaning 1920x1200 next to 1024x1280 much better than 900*1600 assuming they are close in size. Do the number of lines of pixels on each abutting display need to match closely?