Nope, probably not backwards compatible. You will be hardpressed to find a NIC that will work with the older versions of Mac OS.
3com used to make some kickass cards, see if you can find an older one and try to get that to work. You seem to be mostly SOL if you can't find any.
You confused me since in your first post you mentioned Mac OS X, and in my hurry to read it the first time I did not see you wanted it for Mac OS 9.2.2.