GE to Buy SPX Fire Detection Unit  NEW YORK (Reuters) - General Electric Co. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GE.N target=/stocks/quickinfo/fullquote"&gt;GE.N&lt;/A&gt; on Monday  said it would buy a fire detection systems business from SPX  Corp. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=SPW.N target=/stocks/quickinfo/fullquote"&gt;SPW.N&lt;/A&gt; for nearly \$1.4 billion in cash in a move to  bolster its building and security systems unit.