Refinancing and Mortgage Rates?

Are refinancing and mortgage rates different? Also, is refinancing closing cost higher than mortgage closing when buying new home. I bought a home 10yrs-Fixed-ARM in June’07 at 6.25 and now the rates are 5.75. I will save 0 per-month if I get 5.75. Should I refinance? Advise please. I have good credit. http://bit.ly/qmNRZP