Yes, with the right software & hardware you can also rip BD and HD-DVD movies and render a version playable on

TV. However, to be clear, the BD or HD-DVD source is 1920 x 1080, which is beyond what the new

TV can playback. So you have to down-convert such 1080HD video to a format that can play on

TV (720p30fps MAX).
Mac OS X, Quicktime, iMovie, iTunes can all work with full 1080 content, and it will play back in iTunes just fine. But the iDevices- including this new

TV- are limited to 720p30fps (1280 X 720) at best.
So, as I said, SD quality video like DVD, old VHS, SD Camcorder footage, etc are all able to be played back in a full & rich way on

TV hardware. Anything you have that is above 1280 x 720 (BD, HD-DVD, 1080Camcorder footage, etc) all has to be down converted.
The original question was will it look just as good as the DVD. Yes, it will look just as good as the DVD. If we adapt the question to: will it look just as good as the 1080i/p source; no, it cannot look as good because it's not a cross-conversion but a down-conversion. That said, HD sourced content will look very good- better than DVD- even at

TV's 720p level, but I share the above to be complete, rather than implying that better-than-720p content sources like BD quality will also play and look just as good as the original version on disc. It won't because it can't.