FreeBSD 5.4 + DELL CERC SATA 1.5/6ch PCI card (Adaptec)

 I recently bought a Dell SC 1420 server, single  Xeon 2.8GhZ CPU, 
512MB memory, WD 40GB SATA drive, embedded dual channel SATA controller 
> and so far have failed to install FreeBSD.  I have tried 5.4, 5.3, 4.4 
> and after recognizing the drive installation has always stopped at 
> "Waiting 15 secs for scsi drives to settle".  I even tried Mandrake 10 
> and it stalls on hard disk driver installation.  I then disconnected the 
> SATA drive, connected an IDE drive and the system still halted at the 
> same spot.  I have tried to load the aac module but a message early in 
> the boot process states that it was not initialized.  I have done a 
> search in google, WD's website, FreeBSD mailing lists and so far no 
> luck.  What other information do I need to gather in order to solve this 
> problem?  As a last resort I tried and installed succesfully Windows 
98.  I'm hoping that you'll be able to help me with this installation. 
Thank you very much for your help.  Luis