[CentOS] CentOS 5.1 and HP DL145 G2 SATA server configured with Raid

I have a task to set this up, but don't have access to it until I finally I am needed to do it.

If anyone is familiar with this server, do you know if the motherboard based raid is software based (I can't find any real pointer at hp's site)? If so, I suppose it would be better to install CentOS and setup raid inside of Linux. Given that I have never used anything but hardware raid, what should I expect if the primary disc fails? I suppose it would only be a problem once it reboots and the motherboard bios sits and waits to boot the dead disc? Using a real raid hba isn't possible as the only two expansion slots will be full.

Thanks!
jlc