The Washington Nationals apparently decided one of their most-marketable commodities approaching the trade deadline actually is more valuable to them for the long haul. The club and Ronnie Belliard came to terms last night on a two-year, $3.5 million contract extension, a somewhat surprising move considering the attention the veteran infielder was drawing on the trade market and the fact general manager Jim Bowden referred to him as an "asset" upon signing him this spring. Belliard, though, has become invaluable to the Nationals since signing a minor league deal this spring that paid only $750,000 if he made the Opening Day roster. He has wound up filling in admirably at second base after Cristian Guzman suffered serious injuries while establishing himself as one of the clubs most-consistent players.