Intel Shares Edge Lower After Downgrade  NEW YORK (Reuters) - Intel Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=INTC.O target=/stocks/quickinfo/fullquote"&gt;INTC.O&lt;/A&gt; shares slipped on  Tuesday after Credit Suisse First Boston downgraded the stock,  forecasting that the computer chip maker will have difficulty  outperforming the overall semiconductor sector next year.