Katie's Secret Ingredient Smoothie

My cousin Katie (I know, I know...we hear about her alot) intro'd me to this smoothie and it has recently become a serious staple for three reasons 1) my kids love love love it 2) its easy and uses ingredients that do not go bad 3) its extremely low cal but extremely tasty. So....when I diet from the hours of 7 am to 3pm (everyday I fail epically around 3 or 4) I love this little treat. And its filling too!

Katie's Secret Ingredient Smoothie
 This is not an exact science here so I don't have measurements. Having said that, I usually use the following quantities. It makes a blender full.

-3 c. Sprite zero or Diet Twist up (whatever brand of dient lemon-lime soda) <<---psssttt, this is the secret ingredient
-4 scoops Fat Free Rainbow Sherbet (I have only found Wal-Mart brand and its great!)
-2 cups Wal-mart brand's "mixed fruit" frozen fruit (it has mangoes, pineapple, strawberries and peaches in it)