Tech Firm to Acquire Intelligence Contractor SI International Inc. announced plans Wednesday to purchase for \$30 million in cash a Columbia company that specializes in technology work for defense intelligence agencies.&lt;FONT face="verdana,MS Sans Serif,arial,helvetica" size="-2" color="#666666"&gt;&lt;B&gt;-The Washington Post&lt;/B&gt;&lt;/FONT&gt;