HWIC-CABLE-D-2?

Actually they probably do since the cable modem HWIC is DOCSIS 2.0 compliant. Most cable systems providers will support any cable modem that is DOCSIS 2.0 compliant, and most of the large providers use Cisco on the headend anyway. Of course you mileage may very and you should verify with your cable system provider.

Cox unfortunately has a policy of supporting only the modems that are on the explicit list of their own, not by DOCSIS 2.0 approval status.

As far as head end: yes, they most likely use Cisco. But in a really awkward way. For example in the past they had explicit code to disable Cisco uBR series CPE routers. That was in DOCSIS 1.0 days. The disablement was really primitive (they pushed a stupid access list that was easy to disable). But the net result was that the only people who managed to get Cisco uBR 7xx provisioned did so by social-engineering the telephone support and pretending to have other brand of the modem.

Thanks for your time,

Sylvek