Did you try the java options on the Test account? Are you able to install Java 1.5 from there? If your Test account is given admin permissions it can be used for installing apple updates, etc. And also as suggested above, migrating your files from main account across. Then eventually deleting your main account & renaming your Test account. I did that once after my main account became corrupted due to a particular program (not LW).

lol I've misplaced installation disks also (on my G4 I upgraded from 10.1 or 10.2 up to 10.4 step by step over the years).