?????? you do need to connect your comcast cable to your PC via a TV tuner card. I do not know the specs of your TV or display unit so I assume your TV does not have video out. So you a signal splitter (available at amazon or radioshack or mono price) and use one end for TV other end into the PC (PCI addon or USB external) - then use the SW of freetv or media portal to record live Tv. You can use it as a PVR too..
true hemant well said. though if we leave aside encryption and DRM issues what can be done is to add the cable to the PC using a internal/external TV tuner card. And then feed the signal wireless-ly to a linksys router that can be connected directly to the TV using component or HDMI connection. I would have provided the link but the linsys website failed to open on my browser - why not check the linksys site under entertainment products section - they have 2-3 solutions as such. Also I believe quite a few companies like belkin and gefen have such a device - only if my office did not ban so many external websites