What did you use to copy over the files. If it is a seagate hdd it should come with a utility called discwizard and has a file copy utility, I think you can still use it even if you don't have a seagate drive, which is downloadable.
I did the same recently and had a similar problem. Check the jumpers for master and slave, I'm sure you have, in the end I think I had to put them on seperate IDE channels for it to boot up. Make sure the formatting of the new drive was correct and the dos/active partitions have been assigned correctly.
Normally the newer drive will need to be the master. Different BIOSs and ATA controllers can impact this. If you have determined that both ATA drives are jumpered correctly for master/slave and they still do not work, try to bring the new drive up as a stand alone or single drive. If the new drive works fine as a stand alone and fails as a slave, try bringing it up as the master with the original drive as the slave. Jumper changes will be necessary on both drives.
If the drives work in this configuration, there is a decision to be made. You can leave the drives in the working configuration and transfer the necessary data from the original drive (now slave) to the new master drive. If the reverse configuration is preferred, then you will need to purchase a “co-resident” ATA controller. A co-resident ATA controller has two special features. The first is its address is set to secondary, allowing it to be installed in the computer with your original ATA controller, which is set to primary. The second is it has a BIOS onboard that allows two additional ATA hard drives to be installed in your system.