16K would have been a luxury for the ZX81, it only had 1K by default, although you could add an expansion module to get 16K.

As for the Triple Head 2 Go, yep, take a look at the link. The box makes itself look like a single monitor to the PC so it connects to just one output, the three monitors then just connect to it. I have the 24" on the other output of the card.

Most graphics cards have two physical outputs (unless you are using an onboard graphics setup) to which you can connect two monitors.

@cujoe_da_man, if you already have a 6800 card and your motherboard will accept another then yes, you could add a second 6800 (or another pcie card for that matter, although keeping it nVidia would be better for driver compatability). Although, if you wanted to make use of the SLI functionality in games then would need to be another 6800. In non SLI mode, yes you'd have four physical outputs to drive four monitors directly.