When you order a CableCard, you have to request the tuning adapter and they will provide it for you. Otherwise, you'll just receive the CableCard alone. I'm in North Jersey and I literally just ended an online support chat with them and they're sending me the Cisco STA-1520. (The rental fee for the CC covers the tuning adapter - $2.50/mo.)
Did you happen to do a Sefl Install for the that modem? As I understand it the CD that comes with the kit for initial setup also comes with an optional wifi software that can be installed.
It should not harm anything to remove that software if its bogging down your pc.