A possibility would be the direct competitor to the Ultrasharps, Asus Pro Art PA279Q. Was shown off at computex and is scheduled for june release but haven't seen it around yet.
Nice resolution too, 2560 x 1440 no idea on gaming performance or pricing however.
http://www.asus.com/News/HrDwMcYKen95l8ov
However if she is just after a monitor similar to the iMacs display you will do great with the U2713hm, its a great looking screen as with all the ultra sharps and if you get any problems dell will come to your house to replace it. The iMacs only display sRGB so you won't be missing anything there compared to them.
I do however highly recommend the spyder4 if you don't mind the slight investment. You would be surprised how off the colors are, generally a warmer redish hue to everything. Normally £130ish but check the usual places as they can be picked up for closer to 60-70 and for that money totally worth it if you are doing color work such as photography or video editing etc.
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If your planning to do quite a bit of lightroom / photoshop work I would suggest going down the Intel route due to hyperthreading. Those applications make great use of the extra cores. An overclocked 4770k would just scream through tasks and a cheeper route that going with the LGA 2011 setup.
Graphics card wise depending on which games you intend to play decides that, newer titles such as Metro Last Light and Bio shock Infinite I would consider upgrading to a gtx 760 or 770 if your budget allows for eve and supreme commander sli'd gtx 460 will play it no problem as it is quite an old title. Wouldn't go the AMD route for graphics because once again Photoshop and Lightroom will make use of the CUDA cores for adding effect and accelerating the workspace.