The Saddam/bin Laden connection pretty much came from Bush's/Rumsfeld's/Powell's reasoning of going into Iraq in the first place. Mixed in with the WMD rhetoric were things about terrorists and protecting ourselves from another 9/11. I believe there are documented instances where Bush drew a tenuous connection between Iraq and Al-Qaeda in some of his speeches, but ultimately I think there were enough insinuations in the administration's position that people and media completed the connection and ran with it.