Norton is a big pain, I'm going to say it straight out... this is my opinion. It leaves a massive trail of garbage on the OS when you try to uninstall it, even in Windows XP. If there is a way to uninstall it in Windows Vista it is probably going to be very painful, because a good portion of the time when you uninstall it in Windows XP you have to edit it out of the registry as well.
As for Internet Explorer 7, Windows Vista Release Candidate 1 already comes with it. It sounds like you tried to install the Windows XP version from Microsoft.com? I don't understand how IE7 wouldn't start up... what kind of error message are you getting and what are your system specs?