There's a way to forge some registry values so the 1.3 registry key points to the 1.4 directory. I'm using Linux at the moment, so I can't go into the registry editor (regedit.exe in \Windows) and paste in the path to the key. I think it's under HKEY_LOCAL_MACHINE\Software\JavaSoft. You copy the keys and values under the 1.4 branch to 1.3.1 and it makes the installer happy. Maybe someone else who has done it can help you more.