CANNON PIXMA iP6600D ISSUES

I have above printer but Vista Home will not play fair. I'm new to this post and basically to the computer age so please bear with me. Purchased a new desk top and tried to load the software disc for my printer but was warned Vista had issues with it. I did not continue loading! I researched Microsoft and Cannon and found a downloadable driver at the Cannon website that would fix the problem so I downloaded it. I once again tried to load software disc for the printer and recieved a "new driver has already been installed." I'm guessing I need to uninstall original driver but I'm clueless on which driver it is and how to uninstall once I find it. Any help would be appreciated!