I have a question relating to the size of the monitor I want to get. I can get an asus 21.5" monitor for $170, or a 23" monitor for $190 and they both run at the same resolution (1920 x 1080) so I think I want to get the 23" monitor, but I'm not sure if that will decrease FPS. I know the resolution is the same but will my video card (NVidia GTX 260) have to work harder to render on a higher physical area or will it do the same work? This is the only limiting factor between the two monitors because I want to get good framerates on games, so if the extra 1.5 in is going to cause a noticeable decrease in performance I'll go with the 21.5 instead of the 23.
The FPS would be exactly the same between the monitors. Resolution, not screen size, determines FPS. You would also get exactly the same FPS if you were gaming on a 72" 1080p TV. The only difference is that the individual pixels are larger.