Not the best example of the two different type of LCD's available, but it is illustrative never the less.
Both have been calibrated with Eye-One, Display 2. The S-IPS monitor (Dell 2007WFP) on the right has the colors right on - the one on the left is a "TN" variety.
The "TN" one looks a bit darker because that is one part of what makes it a poorer choice in choosing a monitor that is best for graphic or photographic manipulation in Photoshop for example.
I had to hold the camera on the desk for stability, looking up, when I took the pic. The "TN" type must be looked at straight on so as to not get the darker view. Typically the S-IPS monitor has a viewing angle of 178 degrees. The TN matrix is typically less than 160 degrees and looks darker at a greater angle. The S-IPS matrix will have a distinct purple tinge when viewed as a black screen.
I don't believe the really expensive LaCie ($1,000.00 plus) S-IPS monitors have much over this one at $399.00. The last time I looked at the Dell site they did not have the "WPF" listed, only the "FP" - looks the same however. (Now discontinued)
If you do get this monitor the serial number must end in an "L" to be a S-IPS type - Dell has sold both the PVA and S-IPS as a 2007WPF.
Tech Specs for the 2007 WFP DISPLAY:
20.1" / 20.1"
1680 x 1050
16 ms (typical)
178° / 178° (typical)
24 bit - 16.7 million colors