CNNMoney.com reports that during the housing boom, adjustable-rate mortgages (ARMs) comprised 70% of the housing market, but currently make up only five percent.  Freddie Mac says it will be 10 percent by December.  Now they are a bargain at 3.5 percent, while conventional 30-year fixed- rate mortgages are at five percent.  But not everyone is rushing to get one.  The most common ARM would have 3.5 percent for the first five years, and then change depending upon the interest rate.  The poor quality loans that were made five and six years ago, triggering the housing meltdown, occurred in urban areas that are experiencing slow recovery, so now buyers are more skittish about taking a chance.  Plus, as underwriting standards tighten, buyers resetting their ARMs may have a more difficult time qualifying.