Sorry to up this slightly older topic, but I assume the RAID card mentioned would be the one built into the RX100, which is by LSI.
Yes, it will run onder CentOS, but you can't use the Fujitsu installer DVD that comes with the server. However, the normal CentOS install with the RHDUP (download from Fujitsu) on a USB stick installs perfectly and the driver recompiles neatly through kmod on kernel upgrades. I did find I needed to --preload it in grub as otherwise the kernel might see two seperate IDE interfaces on the occasional reboot.
Anyway, we have about ten RX100 S5 and a couple of RX100 S6 all running CentOS 5 without problems. PM if you want to know anything specific (if you haven't got it up and running already).
In my experience the Fujitsu drivers are very stable but the way.