I think I found the answer- I clicked on Tools --> Manage SDK, and then it had "ARM EABI v7a System Image" checked automatically so I just clicked the "Install 1 package" button. It's still downloading- hoping it works.
I didn't see the requirement to download this anywhere in the installation instructions or in the emulator tutorial.
It is only required when you download the platform level for Android 4.0. From my experience this emulator is slower than Android 2.3.3 (API level 10).