I just found this link so it should help you decide which to use I also use their color wizard and the colorfast sheet thingys for the washer in mixed color loads, excellent products and well worth the price.
Stain Devils
Try amazon if you have to order online and a friend of mine finds her as Joanne Fabric but not all of them carry it and I find mine at my local hardware store which I believe is an Ace Hardware. It is Paul's in Iowa City.