Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Sorry I should have made that clearer. I guess Office XP is referred to as "OFFICE10" in program files (correct me if I'm wrong), so I clicked on that when it asked me to browse for an upgradeable product which didn't work. And when I inserted the Office XP disk during the Office 2007 installation and clicked browse and clicked on the drive the XP disk was in, this also didn't work. So i thought I could fix it by uninstalling both Office 07 and XP and reinstalling them, but in control panel the setup didn't respond. So I manually uninstalled both of them (deleted registry values, deleted folders in program files) and now when I try to reinstall 07 it says "Setup can't find a version of Microsoft Office on your computer", and when I try reinstalling XP it doesn't respond. By the way I did download Office 10 free trial and when it expired I went back to Office 2007 which is when it stopped working.
And now I have a new problem. I clicked on the helpful link you gave me and scrolled down to the bottom and uninstalled Microsoft Office 2010 with the Microsoft Fix It utility. Now when I try to install Microsoft Office 2007, I get passed the qualifying product but when I install, it says "the installer has encountered an error" at the very end of the installation.