Help, please!

Hardware: Dell Poweredge 2600
          PERC
          4 SCSI Drives, 1 standalone
                         3 in a RAID 5 configuration
OS: Windows 2000 Server

In other words, a fairly old system. Anyway, we are in the process of taking over support for this site. The current tech wants out and is fading from view fast, so we need to solve this problem:

The standalone disk (where the OS was) failed. We've replaced the disk, installed the OS, but need to know exactly how to proceed from here. I've never worked with a RAID system before, so I don't want to touch anything without knowing what I'm doing.

We are not certain if the site will want us to attempt to recover the array or wait for the old tech to become available. We have replaced the server with a temporary box, and recovered MOST of the data from an online backup service. However, the other tech failed to backup a part of the data and the only copy of it is on this RAID array. Hence, our caution.

We have poked minimally around in the boot-up PERC config utility, and it seems to me that that's where we'll need to be to reclaim the array. Another possibility is that there is some Dell software for the RAID controller we need to acquire.

Can anyone provide clues as to how to proceed from here? Any help GREATLY appreciated.