Hi, Are there any pitfalls I need to be aware of before installing 11gR2 onto Windows Server 2003 with 10g (10.2.0.5.0) already installed? I've searched the forum and found threads on multiple installations in Linux, Solaris and AIX, but not on on Windows Server. The databases will not be run simultaneously. I've looked at the documentation in the 11g Administrator's Guide on Managing Multiple Database Instances on a Single Server. This is not what I'm trying to do. Caging and allocating resources is not going to be an issue. I intend to turn the Oracle Services for 10g to Manual and stop them. Install 11.2 into it's own Oracle Home. This is on a test server. I have a program called Windchill that uses Oracle. I have an existing test environment version of Windchill running 10g. I want to test the latest release and version of Windchill, this requires 11g. I will not be running both at the same time, one or the other. I will start the Ora services for the version that I need depending the version of Windchill that I intend to start. Are there any issues or configuration notes that I should be aware of before installing 11gR2 Enterprise Edition on my test server or the 11gR2 Client on the Windchill test server? I intend to configure both on the same ports for the TNS listener and on the Windchill server the Tomcat and Apache will be configured to use default ports; so both cannot be running simultaneously. Both servers are running: Windows Server 2003 R2 Standard x64 Edition, SP2 Thank you P.T.