Preferred Website(s) for Parts: newegg.com or other depending the deals and quality of parts
Country: looking for quality no real preference
Parts Preferences: by brand or type (intel for the processor had a bad AMD experience)
SLI or Crossfire: yes
Monitor Resolution: I have 2 montiros runnung at 1680x1050 now and will be looking for a third for my card above
Additional Comments: : looking for smooth running, need expert advice
For regular desktop use the single 6850 will run 3 monitors reasonably. However for gaming if you really intend to play at 3x1680x1050, you need to be looking at least a 2nd 6850 for Crossfire, and even then it probably won't be enough to run any high settings. Generally a rig that is intended to run such a setup would be recommended to have two 6950's with 2GB memory which by themselves cost about 250 each and then a 750W PSU would be in the right ballpark to run a suitable setup with those cards.
As for the rest, currently Z68 based mobo with SLI/XFire support with i5 2500k and 8GB of ram is the way to go on that front, but even the 900 will be a stretch if you put in the 2 6950's. But yes, just giving you some generic info, maybe someone will give you a whole setup list.