I am far from a photography expert...but if you really want to take wildlife photos, you will eventaully end up with a DSLR.

I have a Oly E-520. I LOVE the Oly 50-200mm lens. Its light, small, fast and very sharp. The 2x crop factor makes this a nice, light, travel ready combo for wildlife, which is why I bought it. Nonetheless, I am considering switching to the C or N brands for better high ISO performance. I think you would find the same thing given some time behind the camera.