This works in XP not sure about Vista.
Go to "Windows Explorer", Open "C" drive ,Open "Windows", Open "System32" in RH pane scroll down and find 3 files "OGAAddin.dll", OGACHECK.dll, OGAEXEC.exc, and delete these files your message shoud go away and you can use 2003 without a problem. But set updates to "read before installing" and don't download any updates with reference to Office 2003.