The Canon USA site offers versions on the 40D page
. However DPP versions aren't camera specific so the latest version is best downloaded from Canon's latest camera model's page.
It's best to make sure you upgrade all related apps installed on your PC at the same time as Canon reserve the right to change the way they talk to each other. If you don't have any of the apps already installed then the "upgrades" won't install. You'll have to search around on the Net for the registry hacks that will fool the upgrade installer into believing they are already present. And make sure you apply the hack for your OS as they differ. Happy Googling