Question: I can't find a version of one jdk installer. Can I just copy the jdk installation folder from another computer to mine without install it ?

Answer: 
yes you can copy the installation directory, only change you need to do is to change you JAVA\_HOME and PATH variable accordingly...
Are you saying you can't find jdk 1.5, how about this: <http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-javase5-419410.html>

You can also find all the old versions of Java here: 
<http://www.oracle.com/technetwork/java/archive-139210.html>