I am interested in knowing how this device worked out for you if you do decide to purchase it.
If you are curious if your computer will work well with this device, the top link I provided you with, has a link at the bottom of that page where you can run a Digital Cable Advisor program. This way you know before you buy it that it will work well with your system.
I personally think that service is decent customer support.
Looking forward to reading about your experience with this device.
As James has stated, you'll need a cable card from your cable company for HBO etc. to be viewable/record-able, I suggest you contact your cable company first to verify that a cable card is all that is needed to watch those services and that they assign such cards to customers.
It does state that "On Demand
services will not work with this device, however, if you have an addressable cable box, you can connect this device to the USB port on your cable box. I am not sure about using the HDMI port though, some cable boxes have an HDMI output port, I do not have cable, so I can not confirm this, but it is a possible option you can try.