It would be nice if you could turn it over to a certified financial planner and then sleep soundly until retirement. But with that kind of money comes the responsibility to learn how to manage it.
Yes, you SHOULD get with a CFP and discuss how it should be invested. A good one will end up asking you more questions than you ask of him/her. And at the same time, you need to read up on investing. No one is going to care as much about your money as you do, and even though you might get the most brilliant CFP in the world, you still need to understand the reasoning behind the recommendations the planner makes. You also have to understand the tax implications of certain moves because they can weigh heavily on your net earnings.
Understand that $800,000 at 8% will grow to over $3.7 million in 20 years. At 5%, it's $2.1 million. A big difference, wouldn't you say? Knowing what you are doing and having good advisors will make the difference.
To answer your question about the interest, going with a safe 5% return (which would be something like bank CDs or government bonds) would earn $40,000 in a year. Of course, if you are spending the interest, you don't end up with the $3.7 million in 20 years.
jjm, vi_edit, moonbeam and glenn1 all had good advice.
[edit]Just as a footnote, I remember it was just about a year ago that I had a discussion with a member here (I think it was gorth) regarding investing in individual stocks. He was high on JDS Uniphase and had a lot of reasons why it was destined to go up, up, up. At that time JDSU was selling for about $80 a share. Today I noticed JDSU is selling for $10. Individual stocks are too risky for casual investors. If you are going to follow stocks closely, that's a different story. [/edit]