I intend to install a RAID controller.
I have a qx6850 cpu, and an 8800GTX card, and a Gigabyte mobo.
I have three HDDs, two that I use excluseively for FSX set up in RAID 0.
The other I use for the OS and all other applications.
My massive collection of FSX downloads and photographs I have put on to an external HDD - speed is not a requirement.
In the absence of a RAID controller my array is of course managed by the motherboard.
I do not intend to go beyond three HDDs - if the all purpose drive gets too full, I will install a larger one, but the need is not in sight.
There have been dire warnings issued about El Cheapo RAID controllers.