The 40D and 50D bodies are made from a magnesium alloy. The Rebel models are plastic bodies with a stainless steel frame.
Thanks Bob. I'm aware of the body material differences. Unfortunately that wasn't what I was asking. My question was do the plastics hold up reasonably well and to those using plastics, which plastic cameras hold up best for outdoor use and are capable of high quality results. What I'm looking for is a decent plastic body DSLR that could last for several years when treated with reasonable care and works well in the outdoors so I can put a little more money into a decent lens at this point. The 40D and 50D aren't totally ruled out yet, but I'm trying to weigh all my options.
BTW, if it would help anyone in giving me some direction, I'd like to keep my budget in the $1000-$1200 range. Again, I'd like to focus on a decent lens for landscape photography (maybe a little macro work if the mood strikes). Action photography and video aren't the highest priorities for me.