You can't always be sure.

Ken,
You can't always be sure that the updates are legit. That's why you should backup your computer regularly. Get yourself an external hard drive, and set up a backup schedule. I backup my computer every Sunday, so if something does go wrong, or I'm hit with a virus, I always have a recent backup to reinstall. A good one terabyte, external hard drive, and backup software should cost you no more than $200.00. Believe me it's a cheep price to pay for peace of mind. I hope this helps you.
Regards,
TMV