Hi if I delete Explorer 7 from my PC will it automatically revert back to explorer 6?

If you *uninstall* Internet Explorer 7.0, then you will revert to the version of Internet Explorer your version of Windows originally came with. In the case of Windows XP, it would revert to IE6.

Instructions for uninstalling IE 7 can be found here: http://msdn.microsoft.com/ie/releasenotes/default.aspx