Although I was unable to find good search results, I'm hoping someone will have come across this issue before and a solution is at hand 
relevant h/w:
Abit IP35 Pro S775 mobo
2x Maxtor Diamondmax22 SATA-II HDD
1x Pioneer DVR-215 SATA DVD rewriter
1x Sony floppy drive
The system is brand new and the drives unformatted. I would like to RAID the two HDDs. What I'm finding, and hoping there is a workaround for, is that with the OnChip SATA Device enabled and set to RAID the system will not boot from the floppy or optical drive (which I want to use for fdisk partitioning and OS installation respectively).
- With the OnChip SATA Device mode set to IDE, the HDDs and optical drive are recognised on the first POST screen.
- When set to RAID, which I need to access the controller screen to build an array, the HDDs and optical drive are recognised on the second (Intel) screen but not in the BIOS.
I was hoping the system would be smart enough to allow me to run a couple of SATA drives in RAID and use a SATA optical drive. Is there actually an incompatibility here?
Advice appreciated, thanks.

relevant h/w:
Abit IP35 Pro S775 mobo
2x Maxtor Diamondmax22 SATA-II HDD
1x Pioneer DVR-215 SATA DVD rewriter
1x Sony floppy drive
The system is brand new and the drives unformatted. I would like to RAID the two HDDs. What I'm finding, and hoping there is a workaround for, is that with the OnChip SATA Device enabled and set to RAID the system will not boot from the floppy or optical drive (which I want to use for fdisk partitioning and OS installation respectively).
- With the OnChip SATA Device mode set to IDE, the HDDs and optical drive are recognised on the first POST screen.
- When set to RAID, which I need to access the controller screen to build an array, the HDDs and optical drive are recognised on the second (Intel) screen but not in the BIOS.
I was hoping the system would be smart enough to allow me to run a couple of SATA drives in RAID and use a SATA optical drive. Is there actually an incompatibility here?
Advice appreciated, thanks.