An upbeat President Museveni, whose country is involved in the war in the Democratic Republic of Congo, told the BBC that the emergence of a new African Union was important as it would address economic, social and health issues.
"These are initiatives intended to forge Africa ahead in its socio-economic recovery," Mr Chiluba said.
"Africa does not have the luxury of time. We are living in an era where change takes place and is measured in milliseconds."
The close of their summit also marks the transformation of the OAU into a new African Union, which will include a central bank, court and parliament along the lines of the European Union.
The heads of state have also called on Britain to enter a dialogue with Zimbabwe to find a solution to the controversial land question there, but the tone of the resolution was not as critical of Britain as an earlier resolution agreed by African foreign ministers.
Ivorian foreign minister Amara Essy has been sworn in as the new secretary-general to oversee the transformation into the African Union.
Conflict
Earlier United Nations Secretary-General Kofi Annan warned that if Africans wanted to follow the example of Europe after World War II and build a union, they would have to resolve their conflicts.
An upbeat President Museveni, whose country is involved in the war in the Democratic Republic of Congo, told the BBC that the emergence of a new African Union was important as it would address economic, social and health issues.
And he insisted that Africa is less prone to conflict today than it had been 30 years ago.
"This is a struggle, but it is a struggle that is moving forward, as you can see. There are now wars, but they are fewer and on the way out, " he said.
DR Congo
A deal inching forward efforts to end Burundi's civil war, brokered by former South African President Nelson Mandela, has just been announced after talks in South Africa under which Hutus and Tutsis will serve in a transitional government.
But, talks aimed at ending the war in the Democratic Republic of Congo have been postponed for a month.
The former president of Botswana, Ketumile Masire, who has been mediating to end the conflict which has dragged in many neighbours, made the announcement on the sidelines of Lusaka summit.
The talks between Congolese parties and rebel groups are now scheduled to take place in August instead of later this month.
Mr Masire told a press conference that little could be achieved in national all-party talks until the Democratic Republic of Congo was free of foreign troops.
The armies of Zimbabwe, Angola, and Namibia are in the Congo backing pro-government troops against the rebels, who are supported by Rwanda, Burundi, and Uganda.