[CentOS] Controller detection order

Hi,

I have a dell poweredge 850 with centos 4, freshly installed. I'm now  
trying to add in a fibre -> sata raid enclosure with LSI HBA's in the  
850.

My problem is the enclosure gets detected first, hijacking sda and  
sdb from the internal SATA drive and causing kernel panic at boot  
time. I've tried changing the order in modprobe to the following:

alias eth0 tg3
alias eth1 tg3
alias eth2 e1000
alias eth3 e1000
alias scsi_hostadapter ata_piix
alias scsi_hostadapter1 mptbase
alias scsi_hostadapter2 mptscsih
alias usb-controller ehci-hcd
alias usb-controller1 uhci-hcd

previously ata_piix was below the other two.

This hasn't made any difference though. Can anyone suggest any  
solutions?

thanks

Nick