I havent had any problems using the IE7 b2. Besides if you have a good firewall and a good antivirus Attacking a computer is not impossible but it makes it difficult for the people or person to actually attack the DOS. Either way this is still a Beta meaning it has some bugs and only for those who want to test it out.
First of all, OneCare is beta, so be carefull with it. It's not advised to be used by everybody. Only do it when you know what you're doing. It's best to install another av or firewall if you're looking for one like Avast! or Nod32 or mcAfee or ZoneAlarm....
Krypo: It was a complete joke. Was comparing the holes in IE 7 to that of OneCare. I have seen that thing in action & it's like using something worse than AVG free edition. And I do use McAfee.