You won't be able to run audio through your DVI connection and you will have some signal loss but not enough to worry about.
Rather than purchase a DVI to HDMI cable, I'd give Comcast a call and ask them for a new set top box with an HDMI connection without additional costs. Other customers are renting set top boxes with an HDMI connection at probably the same montly price you're paying.
DVI to HDMI connection Is it ok?
Linear Mode
