Stocks Open Higher After CPI, HP Earnings  NEW YORK (Reuters) - U.S. stocks opened higher on Wednesday  after news that core inflation rose only slightly more than  expected last month. Strong earnings from computer maker  Hewlett-Packard Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=HPQ.N target=/stocks/quickinfo/fullquote"&gt;HPQ.N&lt;/A&gt; and a major retail merger also  lifted Wall Street's mood.