These results are in marked contradiction to those of TFT Central, which show a full Adobe RGB gamut for the 2410:
http://www.tftcentral.co.uk/reviews/dell_u2410.htm
I do not see how they can both be right, and the ones herein seem very odd -- how can Dell be selling a monitor with a claimed wide gamut that is not very wide, and does not come close to matching the manufacturer's specs. It is not as if Dell is a small company with no reputation to protect.
Can anyone suggest a way to reconcile the contradiction? Dust on the color checker?