file 1 needs media recovery

This morning I had a hard drive on my Oracle machine die. It was the drive containing the archivelogs.

I've replaced the hard drive, and I am in the process of restoring the archivelogs files from a backup.

Optimisticly, I tried to start the database and got the following errors:

ORA-01113: file 1 needs media recovery
ORA-01110: data file 1: '/oracle_home/oradata/pwhse/system01.dbf'

So, I;m a bit confused about the meaning of this. This file is not located on the disk that failed. Now I suppose that it may have been damaged in a non orderly shutdown of the database. I tried replacing this file with one from last nights hot backup, but I still get this message.

What do I need to do to recover from this?

-- 
"They that would give up essential liberty for temporary safety deserve
neither liberty nor safety."
						-- Benjamin Franklin