If you are having problems finding Older versions (i.e. not 1.6 update 10) most are available here (although single install see notes below):
Archive: Java[tm] Technology Products Download
Head for:
Java 2 Platform Standard Edition (J2SE)
JDK/JRE - 5.0
and select which update you would like from menu, on next screen want JRE
---------
JRE Deployment for System Administrators - The JRE can be distributed to intranet users by hosting the .msi file on an internal website and asking users to launch the installer through msiexec. The other option is to install the JRE through Active Directory. The instructions for these are available in the "Intranet Deployment" section of JRE Intranet Deployment.:
