I just installed RH 8 with a Promise ATA raid and thought I would share the solution to my setup after spending several days here and elsewhere hacking at it.

I have a Gigabyte board with a Promise 20276 RAID 0 (stripe) controller. The array is partitioned for multi-boot with several OS'es (98,W2K, XP etc). I wanted add Linux on a separate hdisk and somehow multiboot this with NTLOADER or GRUB. This is what I stumbled on as the answer.

1) I installed a new IDE drive as a slave (CDROMs are masters) on one of the non-RAID channels. This was now IDE-0 to the BIOS. Windows DM saw it as Disk 0 and the RAID disk as DISK 1.
2) Installed RedHat 8 - "Linux dd" and used the Promise TX2000 for RH 8 from the promise web site.
3) I installed GRUB to the MBR!
4) Set my BIOS to boot IDE-0 not the RAID/ATA.
5) Booted to Linux and modified (added) the grub.conf as follows:

title Windows Partitions
rootnoverify (hd1,0)
makeactive 1
map (hd1) (hd0)
chainloader +1

The RAID array must be hd1 to GRUB?
Now the computer boots to GRUB, I pick the Windows option and it transfers to NTLDR and I can pick whatever Windows OS I want.

During install I could see the RAID array as sd0 but now I don't see this filesystem when in Linux - dont know why yet.

Good Luck and thanks to everyone here and afar that posted to this type of setup.