How can I reinstall bundled software on my Imac G5, with OS X V10.5?

Hello,

Assuming you have the Original Install Discs they should be 10.4.something & will need an external drive to Install to with 10.4.x on it...

Then I think you could use Migration Assistant in 10.5.8 to migrate them.

If it reports a problem of inatalling to 1.4.x, then...

Turn off Automatic Date/Time update in System Preferences, set year to 2005 or such.

The bigger issue is that 10.5 does not work with Classic. Any version of 10.5 you use will have to be retail. http://discussions.apple.com/docs/DOC-2275 tells you what it looks like.