Wal-Mart Same-Store Sales Up 2.4 Percent  CHICAGO (Reuters) - Wal-Mart Stores Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=WMT.N target=/stocks/quickinfo/fullquote"&gt;WMT.N&lt;/A&gt;, the  world's largest retailer, on Thursday said sales at stores open  at least a year rose 2.4 percent in September, slightly higher  than its preliminary report but still toward the low end of its  forecast range.