Do I really need protein powder if I lift weights four times a week?

I lift weights about four times a week, for an hour at a shot, with a good amount of effort. Do I really need protein powder? Some say yes, some say no - only if you are pumping iron for two hours a day. I probably lift weights total four hours a week. My diet is good. I don't trust the nonsense that they put in the commercials these days - all stuff cooked up by an ad exec to get you to buy more.