ASRock Z68 Extreme3 Gen3 LGA 1155 Intel Z68 HDMI SATA 6Gb/s USB 3.0 ATX Intel Motherboard
This motherboard is a Z-68 chipset MB and if you look in the details tab you will notice that the Expansion slots say that the Pci-e slots are version 3.0 and that is for upcoming support for the new Pci-e version which will be activated with a bios update. This feature is available with the Z-68 chipset and not the P67 so if at some point you were to get a cpu (Ivy Bridge) and video card (7970) then you would be able to run this motherboard with Pci-e 3.0.
So it's what is called future proofing which you can't do with the P67 and that may be a good reason to go with the Z-68 motherboard. Not to mention that it will also work great with the i5-2500k and the features of that cpu.
If you are going with three monitors then I would get the 6950/6970/7950/7970
SAPPHIRE 11196-00-40G Radeon HD 7950 3GB 384-bit GDDR5 PCI Express 3.0 x16 HDCP Ready CrossFireX Support Video Card