a. XP will not detect a RAID unless the RAID controller drivers are installed.
b. If you have a RAID setup already and then want to install XP...it all depends on the motherboard whether you need to install RAID drivers beforehand. If the motherboard has RAID controllers as part of the setup...the is something called IDE simulation which can be used to trick XP into not requiring a separate install of the RAID drivers.
Your board has RAID controller built-in...thus you may have been able to install XP without using a floppy to install RAID drivers.
c. RAIDs will always have a separate BIOS for drives used in the setup. These drives will not necessarily appear as part of the regular motherboard BIOS.
Sooo...what BIOS are you trying to enter...and how does it "shut down" on you?
There is no problem with having either 2 IDE drives attached (you have two ports) and it doesn't matter if there is a bootable version of Windows on each or either. What matters is what is set up as boot options in the system BIOS.
If your RAID is your first boot option (it may be reflected as SCSI), then the IDE drives don't enter into the boot picture until/unless you set one of them as a bootable option.
I really can't tell you any more than that, since I have no idea what your BIOS looks like. I have an Asus M2A-VM board but I don't use the RAID.
Consult your owner's manual or go to the Asus website and download look at the manual if you have questions about your board and how to configure it or adjust it.
I see no point in calling anyone when a little reading might suffice...but that's the way I approach things.