Originally Posted by woj

Mortgage is nothing more than a loan, you borrow certain amount at certain interest rate.. the rest, 15 years, vs 30, vs prepaying, etc is all just a smoke screen it makes no difference...

All you need to know is that:
1. you have lets say $200k loan at 5.125% interest rate
2. interest is tax deductible

What this means is that if you are in 25% marginal tax rate bracket, then the effective rate is more like 3.8%*

so then, if you can make more than 3.8%/year by investing in your business or stocks or whatever then you shouldn't prepay...
if you can't, then you are better off prepaying..

*(exact details may vary depending on your situation)