I have ATI graphics, so yours could be different, but normally when I hook up my TV it goes into duplicate mode with max resolution of 720p or something like that, then I go into driver and disable laptop screen, leaving TV as the only display and at that point I get higher resolution options, that my TV supports, up to 1080p. If you don't have that option with LCD screen disabled then look for something to force the resolution, I have that option in ATI driver where I can pick unsupported resolution, in cases where computer does not read TV data properly and it's not aware of all the modes TV/monitor can display. But I don't have Intel graphics, so not sure exactly where and which options do you have. Simple change of resolution is a third option from bottom if right click on desktop in Win 7.
BTW what is the resolution your computer is sending to TV?