I've been facing this issue for a couple of hours now..
On a computer running Windows XP, I could not install Microsoft Office 2010 receiving this message that there was a corrupted Office 2003 installation and there was no way to uninstall it the standard way from the control panel.
After not finding much help about it online, I figured out that an easy way to get through this was to enter the windows registry using Run (Windows Button + R) -> regedit.exe and then search for the term "Office 2003".
It kept on bringing up a pair of two keys including the above keyword in many folders called "Media" and I kept deleting those two keys, until it could be found no more..
Then I tried again and Office 2010 installed just fine.
I hope that I will save some time to others facing the same issue so I'm sharing the fix.
WARNING : Keep in mind that modifying the windows registry is a dangerous tactic if you don't know what you're doing and you may end up losing data or needing to reformat your Windows installation if you're not careful enough.
I was about to do a clean windows installation anyway so I went ahead and tried it and it worked.
Good luck!