Computer is Dell Dimension XPS. Came with one SATA drive (on channel 0). I
installed second SATA drive on channel 2.

I booted from the drive on channel 0, formatted the drive on channel 2 -
everything is great.

Then I disabled drive on channel 0 in BIOS, booted from CD and installed XP
Pro on the drive on Channel 2.

This worked fine as well, I can boot to the drive on channel 2 BUT ONLY WHEN
DRIVE ON CHANNEL 0 IS DISABLED.

In my old Dell computer with 2 IDE drives in the BIOS I could set the boot
order of IDE drives, so I could have both drives enabled and boot from any
of them and see the other one.

It doesn't work this way with 2 SATA drives - if both drives are enabled, it
will always boot from the drive on channel 0. There is no option to make
drive on channel 2 bootable. If I go to the Boot Menu (F12), the only
relevant option there is "Onboard SATA hard drive", and there is no way to
specify which hard drive.

Is this SATA limitation ? Dell motherboard limitation ? Am I doing something
wrong ?

I find it hard to believe it is not possible.