Unless you really want an official Apple monitor, get another brand. They are far less expensive, and in the end they all buy the same panels from subcontracters.
That is not true, like another poster said the Dells use PVA monitors. Not that it is bad, PVA is getting very good these days to the point where even Eizo is starting to use PVA panels in their top of the line displays.
And Eizo displays are top of the line, even above Apple's.
So, basically, there is no advantage in buying an ACD? They are no better quality than other brands?
Nope. It looks cooler and may get you laid, but as a display it has no special characteristic that makes it better than every other display, apart from the fact that it uses S-IPS panels which are a notch above consumer displays based on PVA/TN panels.
Apple does not manufacture their own displays and its been proven that they use the same displays that dell uses.
So how can they be inferior then dells?
Actually they are of inferior quality. The Dells have a higher precision LUT last I heard. The Apple's don't even support contrast controls, so much for making things simple for the user.
There are more than just the panel that comprises a LCD display, the control electronics plays a huge role too.
If you want to properly calibrate a monitor you
need contrast controls.
The only thing about the 23" Apple that is ahead of the 24" Dell is probably the S-IPS panels that Apple uses, but if colour gamut is not a huge consideration it is not like the OP will feel the difference.
Besides the ACDs are absolutely lousy for games due to longer response times, whereas the Dell might actually serve his needs better in this regard. It has nothing to do with Apple bashing or Dell trolling, it is just a characteristic of Apple displays.
If you are serious about your photo editing take a look at NEC's fabulous line of S-IPS/LED backlit professional displays (warning: costs even more than Apple's as hard as it is to believe that Apple's products are not the most expensive in the industry).
If you want to game go for the Dell.