New hard drive boot problem

My son added a Seagate 80G harddrive to his emachines Celeron 500mz
computer. He set the existing 10G harddrive as the slave and the new
drive as the master.

Using the Seagate software three times he tried to copy the info on
the old drive to the new drive. Each time it froze on shut down.
Everything copied to it, but it wouldn't boot. He has erased the new
drive and set the old drive back as master.

Any suggestions as to avoding freezing during shut down of transfering
the info or what to look at to get the new drive to boot?

Thanks,

Dan