Here's the window message I get when I try to open Reader 8.0, "Problem with Shortcut" Then in the window, "This patch package could not be opened. Verify that the patch package exists and that you can access it, if not contact..."
I get the same message when I try to uninstall through Add or Remove Programs in XP Pro.
When I try to download it over the existing install I get a message telling me "Adobe Reader 8.1.2", "Error 1714. The older version of 8.1.2 cannot be removed. Contact your technical support group."
I have just gone through the same problem of uninstalling reader in order to re-install it. The MS Windows Installer Cleanup Utility worked perfectly. Other attempts manually removing as suggested in Adobe's kb400769 had already failed.
Get the MS utility at: