To clarify in my reply #16 it actually gets to the "Press any key to boot to CD" screen and displays "Starting Windows" followed by "Windows is loading files" where it shows "Press F6 to load SCSI drivers," "USB Keyboard," etc. and then finally gives the error message. On further tries it boots fine to Seagate Discwizard boot CD et al but not the Windows install CD which seems to me to indicate something about the device is incompatible with Windows Setup in spite of the fact that it works fine once booted to Windows normally.
I called Vantec support about the problem and was told this is an old, well tested card and assured me it has proven to work without problems for WinXP systems. Obviously they don't even know their own product that well and don't seem to care about trying to resolve issues.
I guess I could keep the card since I'm able to use it once booted to Windows and since I do have a sata DVD-RW I can boot from if needed, but it's a shame it won't work the way it should according to the manufacturer. My other option is to return it to NewEgg for refund, but I suspect return shipping will be at least $5 if not more. Interestingly I have another Rosewill PCI card with VIA chipset that's a sata/ide adapter that boots to Windows CD just fine on another PC, and the Rosewill card cost less than half the Vantec card price.