These NEC's are monitors, made for the computer. If u have a XM29 Xtra (Its written on the front of the TV) the RGB connection in the back are also Pr, Y, and Pb (component cables). You can plug a XBOX360 in 720p or 1080i or any other HD video source. If you have a XM29 Plus, you only have RGB and VGA connectors, good if u have a special cable, but useless for Blurays or most HD video sources. U also have S-Video and RCA inputs. But the quality is MUCH better in RGB/VGA or Component, especially compared to RCA.
Theres no way you'll have advanced remote functions on the remotes. Remember that the original remote even had pin cushion adjustment, overscan/underscan, degauss, and even horizontal/vertical position/size right on the remote. No universal remote will be able to do that.
I dont know what Comcast is really, but if its HD theres a 720p mode probably.
And if u dont know what 720p, 1080i, 480i, 480p is.. then search on the net. tip: resolution)