Thanks for the help 
I did a bit more research. Apparently, the author of the Poseidon stack (Chris Hodges) had a falling out with Elbox when he found out they were selling PCI USB cards with illegitimate keyfiles for Poseidon. So, v3.4 will work with spider.device for a spider 1 card, v3.8 will work with a spider II spider.device, but since then the support for spider.device has been removed 
The kicker is that I can't find Poseidon 3.8 ANYWHERE, and it is probably illegal for me to go asking for a keyfile for 3.8 even if I do find the software...and it's impossible to get a new keyfile.
That sounds accurate, from what I can remember reading a long while ago. I think that is why anyone selling a "New-Old Stock" Spider USB2 card is in a difficult situation, as they can't get a valid keyfile for any version of the Poseidon stack that will work with it and apparently the Elbox stack (if there is one) does not work either.
I am not sure why the latest free version of Poseidon4.4 does not work with the Spider USB cards (and Chris Hodges seems not to know either), but I wouldn't be surprised to find out later that Chris Hodges has still left something in his stack that prevents it from working with the Spider USB cards, because of his lingering anger toward Elbox for what they were allegedly doing with illegal keyfiles for a while. Since I use Subway and Deneb and not any Spider cards, I don't have to worry about these problems and may not be accurate in my guesses, as I have not researched it thoroughly.
