Retailers Seen Posting Modest Nov. Sales  NEW YORK (Reuters) - U.S. retailers are expected to post  modest November sales this week, with No. 1 retailer 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; already cutting its holiday outlook on high  oil prices and warmer weather.