Actually, not much would be different on the civil rights front. Instead of marrying a community organizer, he would have married an elementary school teacher or some such. He would still have given the most foreign aid to Africa, still have Colin Powell and Condelezza Rice, still have renewed the Civil Rights Act. He would still have won a second term, because unseating a President during wartime is incredibly difficult ("War on Terror") and Kerry would still have been swiftboated.
The main difference is that Bush's main character flaw, listening to the wrong people, wouldn't have manifest itself so greatly. Instead of firing Darth Cheney and Donald Duck, he would have kept them on. If it wasn't for her influence, comparing the persecution of the various Iraqi tribes to the persecution of blacks, I doubt Bush would have taken the steps he did to force the Iraqi government to give equal rights to the Kurds and Sunni. Because of Laura, Iraq was ruled by a triumvrate of Kurdish + Sunni + Shia leaders and the most progressive government in the world guaranteeing minority rights, women's rights and human rights. Gunboat diplomacy had a whole new meaning under the Bush administration.
These key decisions probably laid the groundwork for the splitting of Iraq into de facto three countries by the next administration aka Republican government. If it wasn't for that, we might have sectarian strife in Iraq today as these groups would feel marginalized and persecuted. Who knows, maybe Al Qaeda or something much worse could have manifest itself.