I have the following kit: Nikon D200, 17-55mm f2.8 DX, 70-200mm f2.8, 50mm f1.8. The D200 is old, but it gets the job done because the glass is good glass. This outfit does good work for most wildlife shots, you just have to crop the image in the computer when you process the shot. I know very little about Canon products, so I don't have much to say, other than the Chevy/Ford analogy posted earlier seems pretty accurate. I'd point out that the times of day you are most likely to spot wildlife/have the best light to take photos is morning and evening. So you want a lens that will produce good crisp images under those conditions. I bought a Tamron 200-500mm f5.6-6.3 when I first started shooting, because I wanted to really get close. I think I have a handful of useable shots from that lens. It just didn't work because the high f-stop values made the shutter speeds so slow, everything was blurry. I got rid of it and now use the 70-200 all the time. It produces nice crisp images under low light conditions, even if they aren't as zoomed in as the shots I got with the old Tamron. I find that I far prefer a wider shot that is crisp to a close up that is blurry.
Buy a good tripod and a good tripod head and get comfortable operating it. Shooting from a tripod or even a monopod will make a ton of difference under low light conditions. Don't buy one at Walmart or Target. Manfrotto are very nice. The head should be able to rotate freely and quickly, but lock into place and not budge when you want it to.
Also, get an editing program and get comfortable with it. I like Lightroom. You don't need full on Photoshop starting out. A program like Lightroom will give you the ability to look at lots of your photos quickly, and sort out what you like and don't like, and learn what you are doing right and doing wrong.
One last thing, buy a UV filter (a good one) for each of your lenses. Better to break a $50 UV filter than scratch a $1500 lens.
When you get going, start posting on Flickr or sharing your work in some way. It's difficult to start out in any art medium when you are working in a vacuum. You will get better faster with constructive criticism from others who's work you respect. Good luck and have fun.