I got a 24" monitor as well but with a resolution of 1900x1200 and I'm using a FOV somewhere between 60 and 70.
This is based on a FOV-Calculator I found some months back and it very much depends on the distance between your eyes and the screen.
This FOV works great for me in terms of immersion, but I have to sacrifice the real mirrors and can't see anything on the sides.. 60 is really low and at first I found it to be too extreme but it feels quite natural for me now.