This won’t work for Vista. If you are intent on still using Vista you’ll have to find the BIOS slip loader trick to get the proper bios loaded and then you can manually add a PID for digital cableCARD use. I don’t think the generic Win7 PID will work, but it is worth a try if you can’t find one of the old OEM PIDs from Sony/HP/Dell.
Then you’ll have an “iffy” cableCARD system. Vista even with the video pak was no where near as stable as Win7.
You must have a reason for trying it on Vista, but aside from academics, it really isn’t a good way to go. (Been there, done that with OEM Dell and ATI DCT).