Installing CentOS 5 on Compaq Smart Array 2 drives Raid 1 18gb and 3 drives Raid 5 80 GB

Those 2 drives you see during install, is one 18GB and the other the raid5 drive? If yes, then during the installation you can tell the system to use the 18GB drive for your system.

You'll need to select a manual disk setup rather than automatic as the automatic may just dump a load of logical volumes where you don't want them.

As rindi said, you can just select the 18GB drive which should be easy to see in the list of drives available.

This is the root of my question. I can see it  - how do I tell the system to use the 18gb drive for my system? The configuration seems to be working properly since I can boot up with one of the 2 RAID 1 drives installed. But within CentOS  I see one large 73GB drive.

exactly what do you see where in Centos? Do you see the 18 GB array? Where? What is the size of the 3 disks of your raid 5 array? Where do you see that?

 In the CentOS 5 setup I am seeing is 2 compaq smart array drives

 /dev/cciss/c0d0 (17360 mb)
             cciss/c0d0p1 (99 mb)                       /boot>    
             cciss/c0d0p2 (17260 mb)
/dev/cciss/c0d1 (69453 mb)
             cciss/c0d1p1

Device>  > LVM Volume Groups>  
       VolGroup00
                  LogVol00                                      /                                        Ext3  
                  LogVol01                                                                              Swap
HardDrives>
/dev/cciss/c0d0
                        /dev/cciss/c0d0p1                     /boot                             Ext3
                       /dev/cciss/c0d0p2                     volGroup00                    LVM PV
/dev/cciss/c0d1>                
                      /dev/cciss/c0d1p1                      volGroup00                     LVM PV