It's easy to add text to a circle in Illustrator. You just draw a circle, choose the Path Text Tool, click the circle and type. The tricky (and infuriating) part comes when you want to add two different phrases and have one right side up at the top of the circle and one right side up at the bottom of the circle. Here's the trick!
I've used Illustrator CS3 for this tutorial but you can use any version since text on a path was introduced.