SATA Ports not working

Hello,

I have an old Compaq 500B minitower that runs XP Pro. There are four SATA ports on the motherboard that are numbered 1,2,3 and 4. Port 1 is used for the boot hard drive. Port 3 supports the DVD drive. This part works fine.

Ports 2 and 4 are unused. I want to add a second hard drive, specifically a WD Caviar 500 Gig SATA unit. To make a long story short, I cannot get either port 2 or 4 to work, even if the new drive was previously formatted and partitioned in an external USB case connected to the same PC.

As a test, I tried putting the DVD drive SATA cable into these ports. That doesn't work either. I can start the machine and bring up the BIOS. The BIOS can see anything I want to plug into any of the SATA ports,including 2 and 4. BIOS correctly identifies the drives. I can even run BIOS's SMART diagnostics on the new hard drive when it's plugged into either port 2 or 4. No problems were found. The ports and the SATA controller are all enabled in the BIOS.

Then I boot up XP Pro (32 bit) and I can't see anything plugged into port 2 or 4. Ports 1 and 3 work okay. Even when I bring up the Windows Disk Management utility, nothing shows up on 2 or 4. It's like the drive is not even there.

Since BIOS sees anything plugged into SATA ports 2 or 4, but Windows doesn't, I'm guessing I need a special driver. Unfortunately, I can't find one, or any useful information about port 2 or 4. .Any suggestions would be appreciated.