The games will run and look great. The difference isn't the graphical intensity, it's the quality and clarity. I mean, you will still see tje beautiful landscapes and intricately designed clothing. But with an HD TV you will notice them even more.
Can confrim that they still look good, me and a few work mates had a sesh on street fighter 4 at one of there houses on normal TV, looked good but to be honest still looked better on my xbox 360 at home on HD
And the fact that some games will have the black bars on top and bottom of the screen (Widescreen view). Other than that,you should have no problem. :thumbs:
Keep in mind that most PC monitors from within the last two years will have HD hookups as well, you may see if you can connect it to your PC monitor for 1080p HD