crwdns2934241:0crwdne2934241:0 S W

crwdns2934249:0crwdne2934249:0:

Deleted my previous post.  My bad,  I misread your model number.

If it is a G5, and you have a DVD drive, get this from Ebay:

http://www.ebay.com/itm/Apple-Mac-OS-X-10-5-1-Leopard-MB427Z-A-/222499823424?hash=item33ce05df40:g:8A8AAOSwjqVZC8yj

It should boot and let you use Disk Utility to wipe and reinstall OS X to 10.5.1.

crwdns2915684:0crwdne2915684:0:

open