Actually, I was able to increase the drive space of a single partition without any problems. The physical drives in the array were configured with 2 basic NTFS partitions. A C: partition of 4GB and a D: partition of 14GB. After the upgrade, I ended up with a D: partition of approximately 63GB. Here is how I did it:
1. Replaced the 4 9.1GB drives with 4 36.4GB U320 Universal Hard Drives (1"

10,000 rpm (286713-B22).
2. Each drive was replaced one at a time starting with the first data drive 0 and ending with the spare.
3. Installed Windows 2000 SP3.
4. Installed all Microsoft Critical Updates.
5. Upgraded the Compaq Array Configuration Utility to version 2.90.65.0.
6. Upgraded the Compaq Smart Array 431 ROM BIOS to version 1.22 B.
7. Upgraded the Compaq Smart Array-2 Controllers Driver for Windows 2000 to version 5.14.0.0 B.
8. Installed HP ProLiant Array Configuration Utility 1.10.20 (6.20.9.0) a.k.a. Compaq Array Configuration Utility XE.
9. Extended the drive using the Compaq Array Configuration Utility XE.
10. Rebooted.
11. Ran the Microsoft Diskpart Command Line Utility (diskpart.exe) to extend the D: partition and use the newly available unallocated space.
12. Rebooted.