HANOI: Pete Peterson completed his remarkable journey from the bitterness of 6 1/2 years as a POW in North Vietnamese jails to his current post as the first U.S. ambassador to a communist Vietnam when he arrived in Hanoi on Friday. It is no surprise that Peterson says a top priority will be to account for American MIAs. For its part, Vietnam's government wants to use the occasion to push for closer economic ties to the U.S. Although President Clinton lifted a decades-old trade embargo in 1994, Hanoi is still seeking most-favored-nation trade status. But even as the government looks to America to improve the economy, moving on from the agony of war first against the French and then against the Americans is still proving difficult for many people. Although the official line from the government is that the war is history, resentment, though usually kept hidden, persists. Most people do not talk about the fighting, yet nearly every family's household altar has a photograph of a relative killed in the war. Signs are everywhere that the recovery is well under way. The infamous Hanoi Hilton, where American POW's like Peterson were held and tortured, has been demolished. In its place are two office and residential towers.