If you must use an animated banner, make sure you open with a line of text, not some flashy graphic that will deter most users instantly. I don't know about the rest of the users, but my eyes are trained to read words. I might not understand what a particular graphic means, but if you open with a catchy phrase, I'll get it. I usually click on those.
Take Coke Zero. Taste like dung. But with the billboard saying, "Taste so much like coke, we should sue ourselves!" I was sucked into it. In the end, they got more of my money, and I got what apparently is the waste product of coke production.
The point is, I knew what a can of Coke Zero looked like, but in the end it was the catch phrase that caught me. Animated or not, not much difference.