He's tried everything he knows to install it, but nothing has worked. Leo says that there may be a group policy setting that may be preventing him from installing a printer. Go into Group Policies and look for 'Point and Print restrictions'. It may be need to be enabled.
Leo also advises disabling security software to see if that was restricting him. If that won't work, then he may need to do a clean install of Windows 7. It may be something that got messed up during the update process from Windows XP.