Dell Plans North Carolina Plant  NEW YORK (Reuters) - Dell Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=DELL.O target=/stocks/quickinfo/fullquote"&gt;DELL.O&lt;/A&gt; on Tuesday said it  will open a third U.S. manufacturing plant, a plant in North  Carolina employing 1,500 workers, marking a rare example of a  U.S. high-tech company expanding domestic production.