Rayovac to Buy United Industries  NEW YORK (Reuters) - Battery maker Rayovac Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=ROV.N target=/stocks/quickinfo/fullquote"&gt;ROV.N&lt;/A&gt; on  Tuesday said it would buy United Industries Corp., a maker of  lawn and garden products, for about \$476 million in cash and  stock in a bid to diversify its product mix.