If you've already let MS install the KB951748 'security update' (either automatically or through the MS/Windows Update web site) and discovered that you no longer can access the Internet, this might be a tad late for you but the information might help you to know just what happened, etc.
It appears that the KB951748 'security update' and ZoneAlarm do not agree with each other. However, by simply removing the KB951748 'security update' using Add/Remove will restore your Internet connection.
I've included some links below that you can read through.
If you have not already installed this update and use ZoneAlarm....WAIT for now to see what happens next from either MS or ZoneAlarm.
If you do not use ZoneAlarm, you should be OK to install it according to what I've read so far today.