Actualy what you say is a well documented urban legend:
http://urbanlegends.about.com/library/bl_roosevelt_on_immigrants.htm
Emails about the Immigration Subcommittee thing have gone around for a while.
Regardless: we agree... Great statement by T. Roosevelt. The Republicans would be cruising to victory right now if they abided well what he said!
It's not an "urban legend" but historical fact - on Sept.29, 1907, TR appeared before the House Immigration Subcommittee and delivered that message.