Installer.app missing?

I've been having problems with Software Update not actually installing security or application updates, so per advice here, I tried fixing permissions on my HD and then downloading some of the updates manually from the Apple website. Still no joy.

I can get to the point where I have a .pkg or .mpkg file, but instead of being a clickable installer, it's a folder with all the application's files inside.

I did some hunting around the Apple Support site and found this document:

http://docs.info.apple.com/article.html?artnum=60039

That document is about Mac OS X Server, but does Mac OS X client also need installer.app? (I'm running 10.2.8.) I thought it might be on my Power Mac G4 Software Install and Restore CD, but when I tried to launch the Install Applications & Classic Support package to see whether installer.app was in there, I got an error message that says, "There is no default application specified to open the document 'SoftwareRestore.pkg.'" So I guess I can't install installer.app because I don't have installer.app! 🙂

Is my problem related to not having installer.app, or is something else going on?

Once I get this problem sorted out, then I can return to my original problem of Software Update repeatedly wanting to install updates for which my system already has receipts....

Thanks!
Patty