Not sure about the thread you're talking about, but I do have a lot of experience with multimonitor setups (I do IT at a place with a lot of financial traders). A setup like the one you describe pretty much requires two video cards. The only cards I know of that support more than 2 monitors are either Matrox cards, which are over-priced, outdated, and don't support Dual-link DVI for the 30 incher, or nVidia cards like the NVS440 which are are actually 2 video cards on 1 PCB.
Easiest solution is to pick up a PCI video card to drive one or two of the 20's and drive the 30 off your main PCIe card (which will have to support Dual Link DVI). Rotation of the 20 inchers can be handled by the drivers for the PCI card, nVidia, Intel, and ATI all support this function.