IIRC, Siamese system worked also over Ethernet and other serial connections. I think Mini-ITX (and smaller) sized boards fit on the floor of regular PC ATX cases, so one could use the red board (or the blue board). (SAM's second ethernet port would be handy)
I guess Siamese system's SW is available (for update) any more.
Fron the net: "The Siamese System was designed to integrate a PC with an Amiga. It's based around an ISA card which plugs into the PC and takes the output from both the Amiga and the PC and displays it to a single monitor. The system is also designed to transparently share files and peripherals via a serial link through the ISA card. It allows you to share a single keyboard and mouse (either an Amiga or PC) as well as allowing the Amiga to use the PC's graphics and sound card as if they were native devices."
And:
http://en.allexperts.com/q/Amiga-Problems-1522/Siamese-OS3-5-3.htmAlso, one other way is to use mouse&keyboard&monitor swither to use both motherboars of the ATX case. And monitor swither is not needed if the monitor can switch inputs. (currently I use old 19" crt monitors that have two switchable inputs, they cost 5€ each on the local recycling center)
And for the PCI card ... I think sonnet PPC PCI cards are still available, but Hyperion might not be interested to port to those.
