Determine the client who required Windows Update

Should be somewhere in the Assets and Compliance and expand Devices, All Systems. The listing will show those with SCCM client installed as well. There will be more info below it when you select any one of the client device ... there is "client result check"

This is an overall run through blog - good overview
http://mshiyas.wordpress.com/sccm-2012-part-1-installation/

You can create device collection (grouped those clients) and set alert for this collection. In the above blog, it created "All Windows 7 Computers" collection. And in  Software Library >  Software Updates, you can create Automatic Deployment Rules and putting that created collection as the target for update installation. When you come to the part on the Software Update, you can set  filter in the deployment rules whereby meeting the criteria will then apply to the target set.

At times, you may simply just want to deploy selected software updates (can be group base on your criteria on applicability)  directly to the device collection. Simply go to the "Software Update Group" that you create and click "Deploy" ribbon and select the target collection as you are guided through (rather similar) the deployment dialogs...

Hope it helps...if you want to read more, suggest this

http://myitforum.com/cs2/blogs/nbrady/archive/tags/SCCM2012/default.aspx

Works perfect, thank you!