imac 15inch lcd help

[g38]

can anyone help.. ive got this out of mothballs.. for my young son, while upgrading over net we had a powercut and now the hd is faulty, ive been lent a install disk ( form a g5 imac ) but it wont work says it cant install to this computer, i have tried disk repair option it says the drive cannot be repaired and needs formating, so i am i right in saying i need a restore or a bootable osx copy has anyone got these please help he`s doing my head in
regards Paul

[sixyz]

Something to try is a Safe Boot. You should be aware that because of the disk checking, safe boot takes longer than normal startup.

Safe Boot will run a full disk check, and re-run if it finds anything to repair. If it completes the booting process, it will have repaired your disk.

If your machine halts during Safe Boot, you have something seriously wrong with your disk.

If the latter happens, remember this quote from the Disk Utility screen:

• If Disk Utility cannot make repairs, try other disk repair programs or back up your data and erase the volume.

One popular Repair Program is Disk Warrior