Stop Press
As of tonight the NTL web site is not causing problems with framed web sites. The BBC has sort of admitted that their web site code causes framed site to display incorrectly, but it is a low priority to get the code changed.
One thing I have noticed regarding the NTL home page
http://www.ntlworld.com if viewed with IE ver6 the page does not display properly, the middle of the page is blank, if you view the broadband page
http://www.ntlworld.com/indexBroadband.php that has the same sort of information it displays correctly with the middle of the page being used. If you view with IE ver 5 on Win 98 SP2 both pages view correctly so NTL still have a problem that they need to address.
Just in case someone posts try Firefox I have and its the same as above. I have tested it on ver 0.9.1 beta