Q. With a credit score over 770, what would be the lowest possible down payment on a $175,000 to $190,000 loan? We have financed the entire purchase price of our last three houses with piggyback loans.

A. Although it's harder to qualify for 100% financing than it was a few years ago, you should be able to do it. But here are a few things to consider.

First, piggyback loans don't make much sense right now because second mortgages are so much more expensive that primary mortgages. Most buyers are better off getting a single loan and paying for private mortgage insurance.

Even a small down payment, just 5% or 10%, would allow you to qualify for the best rate most lenders offer. If you finance the entire purchase price, expect to pay a quarter- or half-point more for your loan.

And finally, be very careful if you live in an area where home prices are declining. In a couple of years you could end up owing more on your mortgage than your house is worth.

We see that a lot right now, and it's almost impossible for borrowers in that situation to sell or refinance without having thousands of dollars in cash to make up the difference.