In Aug 2007 vs Aug 2006....average sold price in Howard County was up from 1.90% year over year....($493,656 vs $481,551).

In Columbia in particular here is each zip code for August 2007 vs August 2006:

-1.19% for 21044
-4.64% for 21045
-5.00% for 21046

Columbia is not doing as well as other parts of Howard County when comparing these numbers, say Ellicott City 21043, where home prices are up 5.52%. Columbia is essentially fully developed. The others parts of the county have an increase in average sales price due to higher prices of new construction homes.

Understand these numbers also fluctuate from month-to-month...let's look at July 2007 July 2006

-6.20% for 21044
+5.02% for 21045
+.62% for 21046

21043 still did well .... up 12.80% in July 2007 vs July 2006.

Again, I personally don't think Columbia home prices have performed any different than the rest of Howard County due to the new construction higher price sales that beef up the rest of the county.   Columbia is just going through a price correction phase like the rest of the Real Estate market.  I don't believe it will be long before prices stay firm and are level. 

All data is from the Realtor MLS - MRIS.