Internet Explorer 8 required for Windows 2008 SP2 Install

I checked the prerequisites for installing sp2 on w08 at this entry -> http://technet.microsoft.com/en-us/library/dd335038(WS.10).aspx and there is no mention that Internet Explorer 8 needs to be installed in order for w08 sp2 to be installed. And perhaps this is a quirk with Windows Updates, but on identitical w08 boxes (not r2) I am offered SP2 on one and not on the other.

What I AM offered on the other is the installation of IE8 for x64. It has already been installed on the first box. Note that it is simply called 'important' not 'critical'.

So I install IE 8 on the 2nd box and voila! Now I can install sp2.