Comcast extended basic cable can I pick up Hd channels or digital or scale SD?

Hi all I recently looked at an Optoma HD32 and I would like to run cable on it through hdmi, but I am not sure if that is possible with basic cable and also I would like to know if there are tuner boxes that upconvert the signal. Maybe a HD box or STB? Has anyone had a setup for this or know anything about basic cable because I have no clue all I have now is an avermedia tv box 9 that runs vga 480p to projectors. I would like to harness the 720p that the dlp offers. thanks