I'm not a great wildlife photographer or anything, but I agree with fhotoace completely. Some of my pics are taken with a point and shoot camera, but only the ones where the animals can barely called wild any more. Okay, the 18X zoom will let you reach out and touch some of the animals, but if you want to make more than a 4x6 print, you will find that the image quality from the tiny sensor really lets you down.
An entry level DSLR will have a sensor that is about FIFTEEN times bigger than a superzoom point'n'shoot. You can do a lot of cropping on an image from a larger sensor that you just can't do with a P&S.
Definitely go for the DSLR with something like a 70-300 lens, for starters. Most of these were taken with the Nikon 70-300 VR lens:
http://www.flickr.com/photos/samfeinstein/tags/wildlife/