Preheat oven to 350 degrees.
Brown ground beef in a large skillet. When all meat is no longer pink add taco seasoning mix, water and diced tomatoes. Let mixture simmer until most of the liquid is gone.
Put a layer of tortilla chips in the bottom of a 9×13 baking dish. Sprinkle about 1/2 cup shredded cheese onto the chips. Add the ground beef mixture in an even layer (spoon it in rather than dumping it in, or you make a mess of the bottom layer of chips). Add another layer of chips, and then layer the remaining cheese on top of that. Stick in oven for 10-15 minutes, until the cheese is nicely melted.
Serve with a bit of salsa, sour cream, and maybe a few drops of hot sauce. Heck, do all three if you want!
You could also add some onions in with the ground beef, and perhaps top with a layer of shredded lettuce after you take it from the oven.