It's usually best to only install the updates that are selected by default to avoid any possible installation conflicts, then go back and finish installing any other available updates after the first batch are finished installing.
I thought I posted a follow up question yesterday, but I don't see it, so I'll try again.
I looked at my update history, and found that the unselected update had actually been successfully installed a few days earlier
It's still showing up as an unselected, important update. What's up with that?
- - - - - - - - - - - - - - - - - -
Windows Malicious Software Removal Tool for Windows 8 and Windows Server 2012 x64-based Systems - July 2013 (KB890830)
Installation date: 7/11/2013 7:14 AM
Installation status: Succeeded
Update type: Important
After the download, this tool runs one time to check your computer for infection by specific, prevalent malicious software (including Blaster, Sasser, and Mydoom) and helps remove any infection that is found. If an infection is found, the tool will display a status report the next time that you start your computer. A new version of the tool will be offered every month. If you want to manually run the tool on your computer, you can download a copy from the Microsoft Download Center, or you can run an online version from microsoft.com. This tool is not a replacement for an antivirus product. To help protect your computer, you should use an antivirus product.