Investing in real estate used to be considered a "no brainer," a can't-miss investment.

But these days, this sure thing isn't so sure. Home prices keep falling. Standard & Poor tracking shows prices down 7.7 percent nationally in November 2007.

The National Association of Realtors, or NAR, reports that sales of single-family homes were down by 13 percent in 2007, the biggest drop since a 17.7 plunge in 1982.

Representatives of the NAR say that this makes it the best buyer's market in a long time. Prices are down, interest rates are near a 45-year low and the supply of houses is high.

But others argue that with the real estate market in a tailspin, it might be a very long time before prices rebound -- making it a poor market at this time.

Even those who advocate real estate investing concede that you need the right circumstances before you take the plunge.

Who should buy a home?
"Dual-income customers should definitely buy a home now," says George Kaiser, vice president of banking operations for Northbrook Bank and Trust and West America Mortgage Co., its sister company. "People with assets in reserve and a credit score of at least 680 should buy as well. Anyone with a credit score less than that will have to verify their income."

Renters who have stable jobs might find this a good time to try homeownership because of the lower prices, says Scott Rose of Coldwell Banker in Deerfield, Ill.

William Chu, senior mortgage loan consultant, American Chartered Bank, suggests it's a particularly good time to look at the higher end properties if you can afford them because with the pool of buyers shrinking, upper market sellers are lowering their prices to attract a larger pool.

"So if you qualify, you could purchase a more expensive home at a much lower price than you could a few years ago," he says.

However, as always, consumers need to shop intelligently, avoid risk and buy what they can afford.

Definitions

• Risk -- The probability that the return will be less than expected. See the Guide's Glossary for a further explanation of these terms.

Kaiser warns that potential homebuyers must not get in over their heads. They should feel comfortable with their mortgages and be confident they can handle the payments along with taxes and insurance.

Those with lower credit scores will find it a little tougher.

"If you have some credit challenges or less than 20 percent down, be prepared for higher interest rates due to risk-based lending," says Rose.

Who should not buy now?
While prices are more attractive these days, not everyone should be in the market.

"There is no hard and fast rule that applies in all cases, whether it be a good market for real estate or a down market, such as we are currently experiencing," says Valerie Anderson-Jones, CPA, JD, CVA at Kessler Orlean Silver & Co. PC. "Tax advantages can make the ownership of real estate quite appealing, but the decision whether or not to own a home should be based on many factors.

"The size of the down payment and resulting mortgage will play a large part in this decision, as well as the amount of any other assets and debt one currently has."