Dave Ramsey has some great tools for doing that. You won't regret it.
Many sites are available with mortgage calculators that will tell you if refinancing is advantageous. I like the ones at http://www.decisionaide.com/ . Dave Ramsey aside (Yes, we'd all like to be out of debt and rich.), there are valid reasons why refinancing makes sense, and may make your home more marketable. After considering different strategies, find yourself a great LOCAL Loan Officer who can walk you through the Options, explain the Costs and give you honest advice. If your REALTOR is any good, he or she will know several who can be trusted to counsel, not just sell.
Doc Stephens, REALTOR