You know what I don't understand about all of you that want to do this ...

Why would you want to discourage people from returning to purchase something at the site where "I already have an account" and also the fact that by NOT giving people an account you also can't give specific people specific discounts.

Sorry but I agree with Tony on this one - by passing the create an account is basically lying to the customer. I believe that the owners of the 50+ sites I have worked on in the last 2 years would agree.

Just my opinion so take it for what it's worth.