What will be your main use for the new monitor?
Based on your question about calibration, I will assume that photo and/or video editing will be a significant part of what you will be doing. If so, you will also need to consider the "colour space". Will you want a monitor that can show 100% of the Adobe ProPhoto colour space ($$$$) or, since images posted to the web are in sRGB, would a monitor that is capable of displaying the full sRGB colour space meet your needs?
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Typically monitors that you will find on the shelves at your local Staples or Best Buy will not be capable of displaying either of these to 100%.
FWIW, I am also looking for a new computer and monitor. The biggest thing that I do that will be driving my ultimate selection will be photo editing. While I have not totally ruled out an iMac (I am keeping an eye on the Apple refurbished page), it looks as though I will probably be going with a Mac Mini and a new monitor. Like I said, I do a lot of photo editing, but I am not a pro who relies on selling my work to make a living, so for me, I can not justify the expence of getting a monitor capable of the 100% Adobe ProPhoto colour space. I do however post my images to the web and I want to best possible image I can get, so I am looking at
a monitor that will display 100% of the sRGB color space.
I don't know if that helps or not, but I hope it does (or at least gives you something else to consider).