Lets see on a third party auction site we need to buy these. Do you perhaps have these in you home built MCE and it is working with cablecards? I highly doubt it. First you need Vista Ult 64, then you need a main board that is certified with OCAP from CableLabs. There have been no Main boards advertised with OCAP certification in the wild. If there are they are either refurbished or stolen electronics.
As what M$ has stated publicly, the only systems able to have Cable Card support in Vista. Are ones built by OEM's. Last I looked those systems they're were all over 1K. Now you maybe able to configure one on Dell for less but you get less.
If you can do all this by all means show me I've been trying to do this for over 2 years now.