Error message from OfficeProfessional2010_64bit_Setup (running from Download library) says to uninstall MS Off Single Image 2010 and MS Off Professional Hybrid 2007 before rerunning X64 Setup. Neither of these programs is listed in Control Panel "Uninstall or change a program". Win 7 Search on these 2 program names does not return any hits. I am running X64 Win 7.
I read the TechNet article that covers the architecture for 32-bit or 64-bit installation, but this is too general for my problem.
I got in this mess by activating the Office 2007 trial suite preloaded on my computer (Lenovo W700 laptop), then downloading Office 2010 Professional trial X86, THEN purchasing and downloading full Office Professional 2010 X64. I've already uninstalled all Office 2007 programs listed in Control Panel "Uninstall or Change".
I do not wish to cop out and drop back to Office Pro 2010 X86 (very large documents).
I tried to submit this problem to online MS Office chat support; it said it couldn't find my program key automatically. It also said the program key I entered was not valid (this is not true). When I tried to go the charge-my-credit-card path, it said sorry the tech support staff is having problems, and they're working on these problems, and I should submit my request later. It said this to my requests for paid chat, for paid email, and for paid telephone support. (That's a lot of keying in of billing address info, only to be told each time at the end sorry we're busy.)