must be somewhere on the forum, but I can not find it

I still have 6 swu from united, to be used on a flight of Continental AMS-EWR or IAH. Before I book the expensive W class while I can book cheaper in S or K, I would like to know if they will be confirmed straight away. I can see that on UAL.com as NC when booking, what is that code for Continental? Trip still in november, but I hate when they don't come through, while i could have paid less

thanks