Credit score and HELOC question.?

I just got off the phone with an agent, she pulled my credit score and I was at 664, I need to be at 680 to get a home equity line of credit. The agent offered me a refinance option, which would basically cost me 17,000 in closing to borrow 25,000 at 5.8 percent. It really does not bring my monthly payment up much at all..it is like 15.00 extra a month, but now I am basically adding 42,000 to my existing mortgage.I am not to good at math, I have a car loan, by now it is around 10,000 that I pay 380.00 a month on at 11% interest.I am not sure what to do, I can really use some extra money to finsih my yard and maybe possibly pay the car loan. I havea mortgage of 265,000 now and the house is appraised at 500,000. I am not sure if I can raise my credit fast enough, the only thing on my creditis a 400.00 credit card that I make minimum payments on of 15.00 a month. Thanks.