Just an addendum...
Was looking through those U66 troubleshooting questions and there's another one that might apply to you as well (since you're using a WD HDD). In the 2nd thread from the top, it mentions that the Promise U66 card may have issues with certain WD HDDs.
Here is the info:
The only reason that the Ultra66 BIOS will not install is if it doesn't detect a HDD. If you don't have a HDD connected to our card, connect one. If you do, check the HDD jumper settings and cabling. If your HDD is from WD, and it's the only device on the cable, remove ALL the jumpers from the HDD. If the problem still exists, contact tech support with the following information. What are the HDDs that you're using with the Ultra66? What is the jumper setting on each HDD? What is the version of the BIOS on the Ultra66? Make sure the HDDs on the Ultra66 are defined as "None" or "Not Installed" in the CMOS. Are the cables that you're using with the Ultra66 18" or less? Try switching the PCI slot that the Ultra66 is in. Try resetting the configuration data in the CMOS. This is usually an option in the PnP section of the CMOS. The only available settings for this option will be "Enabled" and "Disabled". Set it to "Enabled", save and exit, and reboot.