here is Vince Phillips trying kickboxing
http://www.youtube.com/watch?v=JnY9JsPxBvU

Here is Arthur Williams
http://www.youtube.com/watch?v=c9gjw47NFzI

Here is Ray Mercer
http://www.youtube.com/watch?v=SCXdXtLCt3A

Another Mercer fight. This is not a fair matchup
http://www.youtube.com/watch?v=EXkcYul1LRo

Pretty much goes to show that although the better hands you have the better off you are but boxing can't stand alone against kickboxing.