Tsk tsk.
It depends on what failed. If you are lucky, it's an MBR/partition table problem. If you are less lucky, it's drive electronics. It gets ugly after that.
The usual quotes start at around 800GBP here. Some places operate on a no win/no fee basis. Word of mouth is best, I suggest looking through some of the storage-related newsgroups (comp.sys.ibm.pc.hardware.storage is a good start).
I hope it works out, and please invest the time and the minuscule amount of money to back up your new drive. If it's any consolation, it's happened to most of us.
BOFH