Each time the Oracle Universal Installer is started, it creates a log file. Search for a file called InstallActions.log. If one exists, open and review it for any errors. This may help to troubleshoot why the Oracle install is failing.
Read the installation documentation to ensure that the server meets or exceeds minimum requirements. One of the minimum requirements is 256 MB RAM, which you have, but keep in mind that this is the bare minimum. You may, in fact, require more memory. The installation documentation for Windows 2000 can be found on Oracle's Technology Network here.
This was first published in March 2006