there are a number of issues with ie7 and not just with rockettheme templates. try visiting certian microsoft.com pages with ie7 and you'll also see issues.
its still in beta and probably will be for a little longer.
The problem with IE7 is they attempting to catch up to Mozilla/Safari/Opera in regards to standards but in the typical microsoft manner, they are not following the standards to the letter so it will just mean more headaches for designers to have to come up with creative ways to fix the issues that will undoubtedly ensue. I for one am dreading the day IE7 is released en masse.