Keywiz encoders are generally not USB adapter friendly. You may get lucky and find an adapter that works with no issues, however if after hooking it up and you have problems, it most likely is the fact Keywiz isn't compatible with it.
You could go with something like this:
PCI AdapterHowever, you're probably better going with a GPWiz or an Ipac. If you just bought it, I would see what Randy can do as far as exchanging it...