By Barnaby Phillips BBC Southern Africa correspondent

President Bush is not a popular man in Africa.

His invasion of Iraq provoked anger, scorn and incomprehension across the continent.

A number of issues have aroused African anger

Nelson Mandela described Mr Bush as a man "who can't think properly".

But Mr Bush is coming to Africa, and Africa cannot afford to give him the cold shoulder.

There are a number of reasons why Africa matters to the United States.

Oil

One of them is oil.

The Americans already import about 15% of their crude oil from West Africa; that figure is projected to rise to 25% in the next 10 years.

A series of spectacular discoveries off the coasts of Angola, Sao Tome, Gabon and Nigeria have confirmed the Gulf of Guinea as one of the most strategic regions in the world.

And in the aftermath of 11 September 2001, America is looking to reduce its dependence on the Middle East.

Terror

That ties in with the terrorism threat.

Many African countries opposed the US-led war against Iraq

American officials worry that Africa is the "soft under-belly" in the so-called war on terror.

Al-Qaeda has already launched attacks in Kenya and Tanzania.

Last month the Americans whisked five al-Qaeda suspects out of Malawi, and took them to an undisclosed location.

On this trip, President Bush will be looking for co-operation on intelligence gathering, as well as discussing arrangements for aircraft refuelling and access to military bases in countries across the continent.

Democracy

But the Americans have also learnt that weak governments and civil conflict create the circumstances under which terrorist groups can organise and flourish.

Promoting prosperity and democracy in Africa is not just altruistic - it also serves America's interests.

Fuel strikes could overshadow Bush's visit to Nigeria

That is one of the reasons why Mr Bush has chosen to visit five countries- Senegal, South Africa, Botswana, Uganda and Nigeria - which are all, in their own imperfect ways, relatively successful.

But he will also argue that those African countries which do embrace good governance and democratic values will be rewarded by the United States.

He will draw attention to the African Growth and Opportunity Act, or Agoa - legislation designed to allow African products duty-free access to American markets.

And he will highlight America's commitment to fighting HIV/Aids.

Low expectations

Many Africans will be sceptical. They will argue that American agricultural subsidies undermine Mr Bush's professed commitment to free-trade, and destroy the livelihoods of African farmers.

And already there is considerable doubt as to whether Mr Bush will be able to raise the $15bn he says he needs to fight Aids in Africa.

Mr Bush will never be loved on this continent the way his predecessor was.

When Bill Clinton met the crowds in Ghana, South Africa and Nigeria, the mutual affection was tangible.

His easy, warm style charmed Africans. Even his sexual foibles won him respect.

But, with the benefit of hindsight, many Africans argue that Mr Clinton did not deliver much, despite the hype and excitement that surrounded his visits to Africa.

Mr Bush will be travelling with lower expectations; yet his journey could turn out to be the more significant.