huwyngr

Have you checked to see if there's any relevant settings in the BIOS?

I boot up in verbose mode and I see a text screen very briefly that
relates to my SATA controller -- I'm using internal SATA drives; my
Seagate is USB only. If you watch that carefully you will see a key
code to stop and open it for configuration. Maybe you have to set that
up first?

Have you checked SIIG for updated drivers for VISTA?

Which card is your controller? Although the descriptions include VISTA
in the list of OS's there are no VISTA drivers listed when you look in
support -- that may just mean that it is happy with out of the box
drivers.

Incidentally, if all else fails, run Windows Update / Hardware and see
if it offers a driver for the SIIL 3112 chip that is in their cards
(and my SYBA) although I try to avoid MS hardware updates.