caught in system restore ****! need assistance

hi, im running a 1.6ghz g5 tower. i was running osx 10.3.9 and having some stability problems so i did a system restore, which brought my system back to 10.2.8. i did the archive and install so i have the previous system folder. now im trying to install 10.4, but it doesnt work, presumably because i am not in the 10.3s. i no longer have the 10.3 upgrade disc, and i need to get 10.4 in. it appears to me now that you cannot boot from your previous system folder. is there any way to revert to the previous system? any suggestions?

thanks,
ryan