3 SATA drives, boot problem

i have 2 74gb raptors in a raid 0 config connected to my onboard sata. i purchased a sata controller card and a 250gb sata drive. the system boots fine with the 2 raptors on the onboard but when i plug the sata controller in and initialize the 250gb drive, it keeps wanting to boot the 250gb drive on the controller card and skips the onboard sata startup. if i do not initialize and setup the 250gb drive i have the option of hitting esc to skip and it boots normal(i don't have this option when i setup the drive) does anybody know anyway to make the onboard controller boot before the pci controller card? i would really like to keep the 2 raptors booting from the onboard rather than moving them to the controller card. can anybody help?

i have an Asus A7N8X deluxe rev. 2 motherboard and a PCI Promise FastTrack S150TX 2plus sata controller card.

[Davis]

try going into your bios and set your onboard raid configuration as the primary boot. the card may have changed that setting when u plugged it in.

i don't see an actual raid option in the bios anywhere. in the boot sequence i was told to use the scsi for sata and i am but it still wants to boot from the pci controller card.
are there any keys i could maybe press to make it bypass the pci controller card boot and mit maybe go to the onboard?