Also worth noting on other displays, the Dell displays have great image quality and they are cheaper. I read something earlier today about a new 20" or 24" Dell display that was considerably cheaper again!
Long story short, Dell is not a bad choice for your needs. I went with the Apples as I'm also doing a lot of color sensitive work and after all my research they seem to age a bit better color/brightnes wise than the Dells do.
Mark