Can't install Office 2007 Enterprise

My system came preinstalled with Office 2003 and Office 2007 Beta, i was planning to uninstall them both and install install 2007 Enterprise. I did uninstalled them both and proceeded with installation of Office 2007 Enterprise but now i am getting an error message saying "Setup is unable to proceed due to the following error(s):The 2007 Microsoft Office system does not support upgrading froma prerelease version of the 2007 Microsoft Office system. You must first uninstall any prerelease versions of the 2007 Microsoft Office system products and associates technologies."

It seems as if you have not uninstalled them completely. You might have uninstalled then from add/remove program but your system might be having some file related to them. Just try making search for files related to Office 2003 and Office 2007 Beta manually and delete them if found. You should also remove all references related to them from Registry as well. Once you you are sure that there is no instance of them in your system you can proceed with installation of Office 2007 Enterprise.

A better idea will be using Windows Installer CleanUp Utility for removing Office 2003 and Office 2007 Beta and its related files from your system. I have been using it from a long time for removing old Microsoft office suites and i have never faced any issue in installing new Microsoft office suites by now.