On a 15 year loan, today, there is no reason you should get a rate above 4%. As far as you actual question, it depends. How many years are you in on your 30 year mortgage?

Dont do it. Today rates for par pricing with no points is 3.875. Just pay the extra on your mortgage unless you guy can come to the plate with a real deal.Thats what I have been saying, shop the rate, shop the rate.

The rate should be lower...as pointed out by my colleagues...your scenario is all about the numbers..a professional lender would be able to provide you with loan comparisons demonstrating the differences with staying in your current loan, accelerating the payoff of your current loan and the 15 yr that is being offered. Here is a calculator that you can use..click on the refinance tab and run your own comparison by entering the data...http://www.mycalx.com/calculator1.php?CID=129

Without knowing how long you been paying on your existing loan it would be hard to reply to this question. Generally it would make sense to reduce loan term at the same time lowering the rate. One caveat though is your home under water or do you have an existing FHA loan? to see if you lowering the rate and term will save you more money then adding to the principal use this 20 in one calculator. http://www.lasvegasmtg.com/paymentCalculator.html

How long have you been in your loan? ... Sometimes starting over with a lower rate is not beneficial. .... Happy funding, Rudi