New OS Install - not seeing hard disk

[Walt]

Hello,
We have 2 HP Proliant Servers (one ML370 G4, one ML350-G4p). Both have Smart Array 641 controllers.

During weekdays both servers are in a production environment with RAID 5 setup over 3 disks (one is SBS2003, one is a fileserver).

On the weekends I remove the "Live" disks from each server and install a single Ultra320 disk as a lab environment (I'm studying for certification exams).

The "Live" disks and the "Lab" disk are the exact same make and model. I managed to reinstall Win2003 Server on the ML370 model, but cannot install Win2003 Server on the ML350.

I tried booting off of the Windows disk (as I did with the ML370 successfully) and then tried booting off the HP Foundation CD. Booting from either CD works but once it comes to installing the OS, it stops because it does not see the lab disk.

What am I missing?