Replies to the newly merged posts:
The SA3250 box provided by Cox does work with firewire and is the only one that does. You must subscribe to expanded basic, digital, and HD service to be able to get this box.
You must have the latest version of the firmware for it. You can determine if yours will work by holding down the button in the middle of the + on the front panel till the light comes on, then hitting info. Hit the left arrow. If it takes you to a "1394 information" page, then you're good to go. If it is not, call Cox's tech support and ask that they update the software on your box so you can use firewire. Do not mention that you will be using it to connect to a PC because they won't support it. They need to submit a request for it to be updated, so it might take 24-48 hours for it to happen. Took about 30 minutes for me.
HBO, TNTHD, and PPV will not work, but you should be able to record every other digital channel.
For information on how to record firewire, go read the "How to record via IEEE 1394 (Firewire) to Windows XP" thread right here on AVS.