I am in the market for my first dslr and i have brought it down to three options. A canon rebel xs, a nikon d40 or the Olympus E520. I was wandering also if someone could help explain teh four-thirds system. I am currently using the advanced features on my Kodak z1285 but have grown out of it. All of the cameras above are refurbished. The xs and the d40 are the same price but the e520 is about $60 cheaper. I like to do landscapes and live right under the holding pattern of Newark Liberty so i was also looking to get a telephoto lens later on for that. Any help would be really appreciated and all of the cameras are found on Adorama.com. P.S. I love reading long answers so write as much as you want.