Hello and welcome to the forums. Not sure about its' availability through windows update since I didn't wait and downloaded and installed it as soon as it was available. This is the Microsoft resource I used to acquire the IE9 installation package.
I'm probably not ever going to download or install what is in my opinion a really ugly browser but since installing MSE, my Windows Update settings seem to have been hijacked. Just wanted to make sure that it was at least still working correctly after placing my settings back the way I had them before installing the security software....that doesn't update...even on the hijacked settings....ever.....
But that's another thread somewhere around here probably. Just haven't found it yet.