Mexican Chicken and Spaghetti

4 to 6 chicken breasts; skinned and cooked
    (cook in water and save the water)
1 onion, chopped
1/2 green bell pepper, chopped
2 cans cream of mushroom soup, undiluted
1 pound Velveeta cheese, cubed (or cheese
    of choice, grated)
1 can Rotel
1 small jar pimentos, drained and chopped
1/2 pound spaghetti, cook in the chicken water,
    drain but don't rinse

Cover tightly with aluminum foil, and bake in a 9 x 13-inch casserole dish at 350 degrees F for 35 to 40 minutes.