Preheat the oven to 350ºF. Lightly coat a 2-quart baking dish with non-stick cooking spray; set the dish aside.
Boil the linguine according to the package directions until al dente. Drain well and set aside.
Crumble the ground beef into a large skillet, add green pepper and onion, and cook over medium-high heat until browned. Drain off the fat.
In a large bowl, mix the cooked hamburger mixture, taco seasoning, salsa, cream of mushroom soup, sour cream, taco seasoning, and 1 cup of cheese. Add cooked noodles and mix well.
Pour the spaghetti mixture into the prepared dish baking dish. Top with the remaining cheese. Cover with aluminum foil
Bake the casserole for 20 minutes. Remove foil and bake an additional 10 minutes (until hot and bubbling around the edges). Broil at 450ºF for 5 minutes.