First, read this:http://www.federalreserve.gov/pubs/r...gs/default.htm

From there, I'd ask (or demand) that both the bank and broker provide you with their bottom lines in terms of interest rate, monthly payment, closing costs, any fees that are rolled into the loan and any extra costs (like more insurance or points) to get the rate or payment they're quoting you. If they're unwilling to give you firm figures, tell them it was nice doing business with them and move on to another lender.