Stocks Open Flat  NEW YORK (Reuters) - U.S. stocks were little changed in  early trade on Tuesday, as a report of a possible \$24 billion  takeover of cardiovascular device maker Guidant Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GDT.N target=/stocks/quickinfo/fullquote"&gt;GDT.N&lt;/A&gt;  by Johnson   Johnson &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=JNJ.N target=/stocks/quickinfo/fullquote"&gt;JNJ.N&lt;/A&gt; and easing oil prices provided  support.