I've read reviews on that Acer and apparantly its not bad, but the dell one is a lot better.
I have a 19" dell, and I can honestly say its the best monitor I've ever used, not only is the build quality awesome, (which is what the Acer lacks apparantly), but the screen is pure quality, brilliant blacks, superb whites, and brilliant brightness.
I reccomend the Dell, definitely.
Charlie -