We have 11 years left on our mortgage. Keep plugging on the mortgage. A paid mortgage is a wonderful thing. If you're itching to invest, try opening an automatic investment account at a mutual fund, such as the ones I described in the previous answer. For that question, the best source is your employer.
Most people can do both at the same time.
Getting out of debt is a noble thing, but in the five years you spend paying off your debt, you could be earning money in the market, too. Otherwise, work at both. To me it looks like I can buy a stock at one price, watch it go up during good times and then during turbulent times like today I can watch that same stock go down to where I bought it at. People who preach buy and hold, to me, are typically the lucky folks who lucked out and bought a great stock. I think any rational approach to investing needs a good sell strategy to go along with it.