Circuit City Sales Trail Estimates  NEW YORK (Reuters) - Circuit City Stores Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=CC.N target=/stocks/quickinfo/fullquote"&gt;CC.N&lt;/A&gt; on  Tuesday reported a 2.9 percent gain in quarterly same-store  sales but its growth lagged estimates due to a calendar shift  and reduced spending through August.