It doesn't need a card. But it's very hard to guess what might be wrong. Does the USB port recognise other devices? Can you test the headphones with another computer, perhaps at a neighbour's place?
Behold my tech ignorance! Also, Google is my friend. A little web search provided the answer to the question I did know how to ask. Turns out there was a simple setting disabled on my computer. Once I enable that I was able to find the right port to recognize the headset (with the help of Marie crawling in the floor to plug it into random holes until we found the right one) I dictated this post and it seems to be working well, thanks for the suggestion this sure beats one finger typing. Now I can be more verbose!