I currently have 3 computers that are from 3 to 5 years old

I need to boot to a SATA Raid PCI controller. This will be for a file server
for my home.

I am looking to change from IDE drives to SATA drives.

The SATA drive will be the only drive in the system, unless I need a CDROM
to boot this thing.

Presently on all the computers they fail to boot when the boot device is set
to SCSI. They find not boot device.

It it possible to boot from USB or CDROM and have it boot the SATA drive ?

If so can anyone point me to a HOWTO?

I have tried to create a usb drive using grub to point to the sata drive but
so far I have not been successful in creating a "usb boot device" grub
doesn't seem to work.

What I have done is to copy the /boot filesystem to the usb drive and the
setup grub as:

I point grub to the default device, the usb drive
then issue a root then setup on the mbr of the usb drive.

grub-install --root-directory=/boot sdb

doesn't work for me either

Thanks