Sound like the data might be gone or corrupt at this point. You can always call Dell Support on this, they will take your call even though the server is out of warranty.
If the disks were not initalized, you should be able to clear the controllers current configuration, recreate the RAID 5 array, save the new configuration, then reboot without initializing disks.
I've just successfully tested this using a Dell Power Connect Cache Server with 2 drives configured as RAID 1 and an old Dell workstation that has a PERC II controller in it.
In his particular case, wont this cause a problem if he does not clear the new drive, or actually (the better option?) reinstall the old one? If he recreates the RAID configuration with the new (unwiped) drive in it, how will it know which drive was bad in order to rebuild the array correctly?
Asking because I am not sure, as I have not ever had issues on the rare few machines I have handled that had the PERC II controllers.