A. Most people know they need a surge suppressor - sometimes called a surge protector. However, some don't take the time to think about how they work. Kudos to you, David, for putting some serious thought into your computer's protection.
Just note that a surge suppressor might not be able to save your data from a really vicious storm. That's why you need to have a backup plan - like backup from my advertiser Carbonite. It stores your data in a remote location so it can be the last thing you think about in a bad storm.
Now, on to your question. It may surprise you, but turning off a surge suppressor doesn't totally defeat the purpose. Your computer will be just as safe from electrical surges. But, does that mean it's better to turn it off when your computer isn't on?