If you want the details I'll refer you to the
tftcentral.co.uk specifications page.
Short version with information relevant to you is found in their Buyers FAQ.
The 'normal content' that's referred to is your target group (web visitors). Wide gamut monitors tend to give a much more saturated (oversaturated) image although the Dells have very good sRGB emulation. Still, paying for a feature just to undo it and see approximately what the rest of the world sees seems like a bad idea. The u2711 is wide gamut as well btw, but as there is no alternative with that size/resolution from Dell you can't really say pick the cheaper one. Hazro, HP, Fujitsu, Samsung and soon Lenovo and ASUS do/will have alternatives though.
If you do photo editing for printwork then I think getting both a u2410 and u2412m would be your best option. Leaves you with both a standard and wide gamut option and with one u2412m the costs will be reduced quite a bit.
If you can you may want to wait for input from someone who actually knows his stuff when it comes to these things though. All my knowledge is from my own interpretation of what's written on the web. Never used a wide gamut myself