I want buy a canon 40d. What is the differancen in a gray market camera and a usa model?

Canon USA will not service it if it needs repair.|||Stay away from gray market. There is no US warranty. buy from a place like circuit city or best buy. or a camera shop. But go with the 50d. new model. same camera just a higher mp. but stay away from anything gray.|||besides the warranty...there's really no difference...I've purchased gray market lens and had no problems. IMO, for the price of the 50D, I'd rather stick with the 40D and get a lens.