Sorry I wasn't more clear in my original problem statement.
I have a single server computer that I want to be responsible for hosting all of my KD sessions on the same desktop. I frequently run KD sessions on multiple test PC's at the same time. My desk right now contains... let me count... 10 test laptops, about 7 of which have 1394 ports and can be debugged. One or two of them have RS-232 ports but I don't like to debug with RS-232 because it's slow and unreliable compared to 1394, and the slowness of the debug spew frequently changes the timing of the PC such that it changes the repros (i.e., something that repros on a retail build off the KD will not repro on the RS-232 KD because it's so slow). Some of them can be USB debugged but that is SUPER difficult to set up, is unreliable, and had bugs such as there is one laptop which locks up when you suspend/resume on the USB KD.
My server computer has a 1394 card inserted in it, which has three usable external ports. That means I can debug only 3 test machines at the same time. I want more.
I tried adding a second 1394 card only to discover that WINDBG doesn't support multiple 1394 cards, even in the latest version. I shopped for 1394 cards online but they all have, at most, three firewire ports. (Any of the cards with four ports, you come to find out that the fourth port is internal, and is a hard-wired duplicate of the third port, and you can't use the internal port at the same time as the external port. I discovered this the hard way too.)
So all that's left for me is a hub. When I posted yesterday, I was going to order one through our IT guy, and was hoping that I could find out if it would work before spending money on it. Well, it turns out he had one lying around already, so I plugged it in.
So far I've only tried it with one PC chained straight through the hub. That works. Hopefully I'll be able to get more devices plugged into it and confirm that it'll work with multiple devices. Crossing my fingers.