And, you can have several logins, and switch with the F keys. Some can be X, others shells.
I have 3 monitors on my latest machine, all LCDs at 1280*1024. I will seriously need to see if it is efficient in view of this article. But I do like being able to see data sheets for the microprocessor etc on one screen while designing hardware or maybe software on the second, and maybe copying and pasting bits of code from the third. And, I can quickly toggle between that and several games of Mahjong!
I am only using cheap Nvidia cards, a dual head AGP and an old single head PCI, but SuSE was easy to set up (not using Sax, which trashes Nvidia setups) and BSD amounted to copying the SuSE XF86Config file over and making a few changes where things are different in BSD, not the hard bit like the monitor settings.
I don't know if it would work in Windoze, that machine has never seen any trash Monopoly code and never will.