need help resetting username/password??

Hi guys and gals im new to macs so please be patient with me.

I have just bought a Powermac G5 1.6 of Ebay to replace my G4 1.25 MMD and its awesome.

The trouble is that when the last owner upgraded to a mac pro they put a fresh instilation of 10.5 on and now have forgotten the password and im left without any disks to put a fresh install on.

I have looked on the net and found the
Boot into single user mode (press Command-S at power on)
Type fsck -fy
Type mount -uw /
Type launchctl load /System/Library/LaunchDaemons/com.apple.DirectoryServices.plist
Type dscl . -passwd /Users/username password, replacing username with the targeted user and password with the desired password.
Reboot
methord but I cant get that to work. is there any other way as I dont want to have to spend £100 plus for a fresh copy or 10.5.6

Any help would be much appreciated.
James

Sorry I can't help with the commands, but I wouldn't recommend not having the install disks. You may need them - more than likely!

Contact the seller and ask for the Leopard disks. Since he put Leopard on the machine he must have the disk set - which he should have included with the sale. Either that or purchase Leopard for yourself. You need to have the media anyway in the event you ever have to reinstall.

Regards.

Ok cheers. I has the leopard disk made a copy as a back up for my self then sold the original to a friend. I tried the leopard on my G4 and it worked, could it be my dvd drive that doesnt read coppied disky? Has anyone ever heard of this?
James