Dreft is very far from a "free and clear" detergent. There is absolutely no reason to use it- not on diapers, not on clothes. It's all marketing. Definitely donate it or return it. I mean, if you're going to all this trouble to get an environmentally friendly and baby friendly detergent for your diapers, why use crap for the rest of your clothes? It's sort of like going to all the trouble of making your own cleaning products just to clean the bath tub where you will bathe baby, but using bleach for the rest of your house. At least, that's my thought...
There are a million detergents you can get that are usually available locally. I personally buy Planet by the case through our local UNFI co-op and Amazon has it for a decent deal as well. Here are some websites to check out for detergents:
http://www.pinstripesandpolkadots.com/detergentchoices.htm (click the HE link if you have a front loader)
You'll see that Dreft gets an avoid rating. With the Ecos, you need to be sure to get the free and clear, not the one with fabric softeners.