Bright, red-lettered banners bearing the words of the sainted communist leader Ho Chi Minh (1890-1969) hang from government buildings in Hanoi and other cities and towns throughout the Socialist Republic of Vietnam. But few citizens now pay much attention to once-rousing slogans. With fully half of the present population born since 1975, Vietnam is in more ways than one a new country. Today, its citizens are more concerned with the everyday demands of the present than with the struggles, however heroic, of the past- a reality that may well distress the aged veterans of Dien Bien Phu and other memorable battles, taking their ease in the parks along the shores of Hanoi's lakes. But ambitious city dwellers, working hard to earn a living by day and then, in many cases, learning Wordperfect for Windows, or studying English, or holding down a second job by night, are too busy to care about that. As for the farmers, who still make up three-quarters of Vietnam's 73.5 million people, their overriding concern is the same as it has been for 2,000 years: to plant the next rice harvest.