Absolutely you can use as 5.1. That is the way mine are configured. In the speaker config menu just make sure the back surrounds are shown as "none". If you want to go to 6.1 before 7.1 you can do that also by hooking up to the left back surround and changing from "none' to BS
No question is too simple: I asked a ton when my 950 was new. Enjoy; the 950, even with its quirks, sounds great