MSI Raid Configuration

Hello,

I just purchased a MSI K7T266 Mobo for a system I am building.

I have a few questions:

1. What is the best way to make use of the on board RAID?
The tech that works for me does it this way: Install a 40GB HDD on the main IDE channel to run the OS and other software and then use the RAID drives to store the data. I imagine the alternative to this is to just load the OS and everything on the RAID drives. What are some advantages/disadvantages of either configuration? Are there any other possible configurations? Note: I am planning to use mirroring.

2. The manual says that the board will only take 4 IDE devices. Does that include the RAID IDE channels? For example, does this mean that if I had 2 drives for the RAID, and then a DVD-ROM, a CD-RW, and a some other IDE device (total 5, 2 on the RAID, and 3 on the normal IDE channels) that I could not have all 5 attached to the board? It just seems to me that would suck.

I would appreciate any information. Thanks