Hi Stephanie:
I don't know if this will help you much, but I have two scriptures that have made an impact to me in proving that the JW was not the truth
Deut 18:22 "If what a prophet proclaims in the name of the Lord does not take place or come true, that is a message the Lord has not spoken. That prophet has spoken presumptuously. Do not be afraid of him." Now...how many times has the organization made a "prophecy" that has not come true? Your friend will answer that the Organization does not claim to be a prophet - but if you do some research you will find that in fact they have said just so in their own literature. Besides - if you look up the definition of a prophet I'm sure that the actions of the society fit.
Matthew 24:26-27 - This one basically says that if someone claims Christ has returned in some hidden way it is not true because his return would be seen by everyone.