Since you want triple monitors, you could go for Ivy Bridge. It has better graphics than Sandy Bridge and can support 3 monitors. If you want a resolution higher than 1920x1200 across all displays, you will have to go for discrete graphics.
I use HP ZR24w at work which supports 1920x1200. HP ZR2740W is a new product which supports 2560x1600 resolution.
a few things;
first, HP ZR24w seems like an old model, shouldn't there be a better model at a better price nowadays?
secondly, is a i5 really necessary? could I manage with Intel Core i3 530?
and if you were to choose a mobo for an i3-530, which one would you take and why?
Newegg says that core i3 530 is deactivated (will not be restocked). Now that Ivy Bridge is coming out, you could get a good deal on core i3-2100 which is a pretty good chip at ~$130. You could also go for Sandy Bridge Pentium G850 available for ~$90. You can put a more powerful Sandy Bridge or Ivy Bridge later if you so choose.
If money is a big constraint go with H61 chipset motherboards - that will continue to be the value chipset in Intel's lineup in 2012.